What are the northern lights?(Everyday Mysteries: Fun Science Facts from the Library of Congress) What are the northern lights? The northern lights, one of several astronomical phenomena called polar lights (aurora polaris), are shafts or curtains of colored light visible on occasion in the night sky. Polar lights (aurora polaris) are a natural phenomenon found in both the northern and southern hemispheres that can be truly awe inspiring. Northern lights are also called by their scientific name, aurora borealis, and southern lights are called aurora australis. Sten Odenwald, author of The 23rd cycle, learning to live with a stormy star (New York, Columbia University Press, c2001), provides insight to how northern lights are formed: The origin of the aurora begins on the surface of the sun when solar activity ejects a cloud of gas. Scientists call this a coronal mass ejection (CME). If one of these reaches earth, taking about 2 to 3 days, it collides with the Earth’s magnetic field.

This field is invisible, and if you could see its shape, it would make Earth look like a comet with a long magnetic ‘tail’ stretching a million miles behind Earth in the opposite direction of the sun. When a coronal mass ejection collides with the magnetic field, it causes complex changes to happen to the magnetic tail region. These changes generate currents of charged particles, which then flow along lines of magnetic force into the Polar Regions. These particles are boosted in energy in Earth’s upper atmosphere, and when they collide with oxygen and nitrogen atoms, they produce dazzling auroral light. Odenwald further tells us "Aurora are beautiful, but the invisible flows of particles and magnetism that go on at the same time can damage our electrical power grid and satellites operating in space. This is why scientists are so keen to understand the physics of aurora and solar storms, so we can predict when our technologies may be affected." Can I see them anywhere? Yes. Although more frequent at higher latitudes, closer to the poles (such as in Canada, Alaska, Antarctica), they have been seen closer to the equator as far south as Mexico.

To view them, look in the direction of the closest pole (the northern horizon in the northern hemisphere, the southern horizon in the southern hemisphere). Can I see them at any time of the year? Yes. In some areas, such as Alaska or Greenland, they may be visible most nights of the year. And they occur at any time of the day, but we can’t see them with the naked eye unless it’s dark. What causes the colors and patterns? Colors and patterns are from the types of ions or atoms being energized as they collide with the atmosphere and are affected by lines of magnetic force. Displays may take many forms, including rippling curtains, pulsating globs, traveling pulses, or steady glows. Altitude affects the colors. Blue violet/reds occur below 60 miles (100 km), with bright green strongest between 60-150 miles (100-240 km). Above 150 miles (240 km) ruby reds appear.

Fun Facts about northern lights: According to Neil Bone (The aurora: sun-earth interactions, 1996), the term aurora borealis--northern dawn--is jointly credited to have first been used by Pierre Gassendi (1592-1655) and Galileo Galilei (1564-1642), who both witnessed a light display on Sept. 12, 1621. However, Bone also includes a description of the northern lights made 1,000 years prior by Gregory of Tours (538-594.) It included the phrase, "... so bright that you might have thought that day was about to dawn." Auroras have been observed since ancient times. The height of the displays can occur up to 1000 km (620 miles), although most are between 80-120 km. Auroras tend to be more frequent and spectacular during high solar sunspot activity, which cycles over approximately eleven years. Some displays are particularly spectacular and widespread and have been highlighted in news accounts.

Examples include auroral storms of August-September, 1859, Feb 11, 1958, (lights 1250 miles wide circled the Arctic from Oregon to New Hampshire) and March 13, 1989, (the whole sky turned a vivid red and the aurora was seen in Europe and North America as far south as Cuba). Legends abound in northern cultures to explain the northern lights. Some North American Inuit call the aurora aqsarniit (“football players”) and say the spirits of the dead are playing football with the head of a walrus. Often legends warn children that the lights might come down and snatch them away. June 1896, Norwegian Kristian Birkeland, the “father of modern auroral science,” suggested the theory that electrons from sunspots triggered auroras. Yellowknife (Northwest Territories, Canada) is the capital for aurora tourism. The earliest known account of northern lights appears to be from a Babylonian clay tablet from observations made by the official astronomers of King Nebuchadnezzar II, 568/567 BC.

Some people claim to hear noises associated with the northern lights, but documenting this phenomenon has been difficult. Related Web Sites Aurora borealis by Pål Brekke - This is an article on the aurora borealis by Pål Brekke published in Scandinavian Review, Fall 2008, v. 93. Auroras: Paintings in the Sky - Lots of links, pictures, includes specific information for teachers. Cosmicopia: an abundance of cosmic rays - Information on Space Weather from NASA, including an animation of a coronal mass ejection's impact on the Earth's magnetosphere. NOAA POES Auroral Activity - Technical information and data collected from POES (Polar-orbiting Operational Environmental Satellite) on its most recent polar pass. May help predict where to see auroras. Solar Storms - This site presents information about the human impacts of solar storms and space weather. Space Weather Research Explorer: Auroras - With data from POES, this Exploratorium site packages the information in a simpler format. Further Reading Northern Lights or Aurora Borealis Explained What are Northern Lights? The bright dancing lights of the aurora are actually collisions between electrically charged particles from the sun that enter the earth's atmosphere.

The lights are seen above the magnetic poles of the northern and southern hemispheres. They are known as 'Aurora borealis' in the north and 'Aurora australis' in the south.. Auroral displays appear in many colours although pale green and pink are the most common. Shades of red, yellow, green, blue, and violet have been reported. The lights appear in many forms from patches or scattered clouds of light to streamers, arcs, rippling curtains or shooting rays that light up the sky with an eerie glow. What causes the Northern Lights? The Northern Lights are actually the result of collisions between gaseous particles in the Earth's atmosphere with charged particles released from the sun's atmosphere. Variations in colour are due to the type of gas particles that are colliding. The most common auroral color, a pale yellowish-green, is produced by oxygen molecules located about 60 miles above the earth. Rare, all-red auroras are produced by high-altitude oxygen, at heights of up to 200 miles. Nitrogen produces blue or purplish-red aurora. The connection between the Northern Lights and sunspot activity has been suspected since about 1880.

Thanks to research conducted since the 1950's, we now know that electrons and protons from the sun are blown towards the earth on the 'solar wind'. (Note: 1957-58 was International Geophysical Year and the atmosphere was studied extensively with balloons, radar, rockets and satellites. Rocket research is still conducted by scientists at Poker Flats, a facility under the direction of the University of Alaska at Fairbanks - see web page The temperature above the surface of the sun is millions of degrees Celsius. At this temperature, collisions between gas molecules are frequent and explosive. Free electrons and protons are thrown from the sun's atmosphere by the rotation of the sun and escape through holes in the magnetic field. Blown towards the earth by the solar wind, the charged particles are largely deflected by the earth's magnetic field. However, the earth's magnetic field is weaker at either pole and therefore some particles enter the earth's atmosphere and collide with gas particles. These collisions emit light that we perceive as the dancing lights of the north (and the south).

The lights of the Aurora generally extend from 80 kilometres (50 miles) to as high as 640 kilometres (400 miles) above the earth's surface. Where is the best place to watch the Northern Lights? Northern Lights can be seen in the northern or southern hemisphere, in an irregularly shaped oval centred over each magnetic pole. The lights are known as 'Aurora borealis' in the north and 'Aurora australis' in the south. Scientists have learned that in most instances northern and southern auroras are mirror-like images that occur at the same time, with similar shapes and colors. Because the phenomena occurs near the magnetic poles, northern lights have been seen as far south as New Orleans in the western hemisphere, while similar locations in the east never experience the mysterious lights. However the best places to watch the lights (in North America) are in the northwestern parts of Canada, particularly the Yukon, Nunavut, Northwest Territories and Alaska. Auroral displays can also be seen over the southern tip of Greenland and Iceland, the northern coast of Norway and over the coastal waters north of Siberia.

Southern auroras are not often seen as they are concentrated in a ring around Antarctica and the southern Indian Ocean. Areas that are not subject to 'light pollution' are the best places to watch for the lights. Areas in the north, in smaller communities, tend to be best. When is the best time to watch for auroral displays? Researchers have also discovered that auroral activity is cyclic, peaking roughly every 11 years. The next peak period is 2013. Winter in the north is generally a good season to view lights. The long periods of darkness and the frequency of clear nights provide many good opportunities to watch the auroral displays. Usually the best time of night (on clear nights) to watch for auroral displays is local midnight (adjust for differences caused by daylight savings time). Legends of the Lights 'Aurora borealis', the lights of the northern hemisphere, means 'dawn of the north'. 'Aurora australis' means 'dawn of the south'. In Roman myths, Aurora was the goddess of the dawn. \par Many cultural groups have legends about the lights. In medieval times, the occurrences of auroral displays were seen as harbingers of war or famine.

The Maori of New Zealand shared a belief with many northern people of Europe and North America that the lights were reflections from torches or campfires. The Menominee Indians of Wisconsin believed that the lights indicated the location of manabai'wok (giants) who were the spirits of great hunters and fishermen. The Inuit of Alaska believed that the lights were the spirits of the animals they hunted: the seals, salmon, deer and beluga whales. Other aboriginal peoples believed that the lights were the spirits of their people. University Lowbrow Astronomers Naked Eye Observer’s Guide. Naked Eye Observer’s Guide by Dave Snyder Written: February, 2000 Revised: September, 2005 This page has a variety of suggestions for beginning amateur astronomers who wish to observe the sky with only the unaided eye. It is a common misconception that you need to have a telescope to do astronomy; this simply is not true. A wide variety of objects can be seen with the naked eye: from planets and stars, to nebulae and galaxies.

While you can usually see more detail if you use a telescope (or binoculars) and you can usually see more objects of a given type if you use a telescope (or binoculars); the same types of objects that can be seen with a telescope can be seen without a telescope. If you’ve decided you want to observe the night sky without a telescope, you will need some idea of what to look for. Even if you have a telescope or have made a firm decision to purchase a telescope, it is a good idea to look at the sky without optical aid. The time you spend will give you ideas on where to look and what to look for in a telescope. It will also enhance your observing skills. Magnitudes Some things are brighter than others: Astronomers use an extension of a system invented in the second century B. C. to describe brightness of objects. Most objects are assigned positive numbers: The larger the number the dimmer the object (magnitude 3 is dimmer than magnitude 2). Very bright objects are assigned negative numbers; this is true of the sun, the moon, bright planets and the brightest stars. Again the larger the number, the dimmer the object (magnitude -2 is dimmer than magnitude -3).

Here are a few examples (note these are typical values, values may be larger or smaller under some conditions): Magnitude -27 The dimmest objects on a photographic plate produced with a large telescope As mentioned above, the dimmest object visible with the naked eye is typically magnitude 6.5. However this magnitude (called the magnitude limit) can vary. Many factors affect the magnitude limit: Pupil dilation - When you first go outside at night from a brightly light room, you probably not be able to see anything except the brightest objects, but if you wait a few seconds or so, your ability to see improves dramatically. Dark adaptation - When you are in the dark, your retina gradually adapts to the light level; most of this adaptation occurs in the first half-hour. Dark adaptation will not be complete if there are bright lights; once established dark adaptation can be lost very quickly if you subsequently encounter bright lights. If you need a flashlight, it is best to use a dim red light. Such lights are less likely to interfere with dark adaptation. Light Pollution - Even if you find a site away from city lights, the site still may not be that dark. You may see a glow near the horizon.

Large cities can be seen as such a glow as far as a hundred miles away. Smaller cities can be seen from tens of miles away. When there is a glow on the horizon, there is often stray light all over the sky and this stray light will reduce what you can see. Snow - Significant snow cover can have the same effect as light pollution and can reduce your limiting magnitude. Clouds - Complete cloud cover can prevent you from seeing anything, partial cloud cover often reduces the limiting magnitude. The Moon - The light from the moon reduces your ability to dark adapt. The limiting magnitude is larger (dimmer) when the moon is not visible. Altitude - Objects close to the horizon often are obscured in haze. Thus the limiting magnitude is smaller near the horizon than it is near the overhead point. Experience - Someone who has observed for many years typically can see objects one magnitude dimmer than an inexperienced observer. Age - As we get older, our retinas become slightly less responsive, however this will only be a few tenths of a magnitude. The effect of experience is more important than the effect of age. Alcohol - Alcohol depresses the dark adaptation response. Nicotine - Cigarettes and other sources of nicotine also depress the dark adaptation response.

Object Size - Extended objects (like galaxies or nebulae) are often harder to see than objects that appear to be points of light (like stars) if both objects have the same magnitude. Object Color - The limiting magnitude for red objects is lower than the limiting magnitude for objects of other colors. For information about light pollution and what you can do about it. Observing Sites The first step in astronomical observing is selecting an observing location. If you planning to observe bright objects, such as planets, it may be best to pick a site that is convenient, such as a place close to home. If you are planning to observe dim objects you should pick an observing site that maximizes your limiting magnitude. It often helps to observe near the time of the new moon, so the moon doesn’t drown out the light from dim objects. In many cases it is helpful if there is a good horizon; such a location will have few obstructions such as hills, mountains, trees or buildings. It is also a very good idea to abstain from alcohol and nicotine before and during an observing session. The limiting magnitude at suburban locations is typically 3.5, and the limiting magnitude at dark sites is typically 6.5.

Experienced observers at very dark sites have reported limiting magnitudes as high as 8.5. Constellations If you want to find your way around the sky, you need to learn the constellations. Constellations are groupings of stars created by astronomers; many of the modern constellations were borrowed from constellations invented by ancient peoples. The existing constellations are not always the best groupings possible; there are many groupings of stars that seem like they should be constellations, but are not. Such groupings are called asterisms. Which constellations are visible vary depending on your latitude, the time of day and the time of year. In general, at a given location, some constellations will always be visible (they are called circumpolar), some are visible part of the time, and some are never visible. One way to learn constellations is to first learn a few landmarks. The best landmarks vary depending on time of night and the season, in the Northern Hemisphere the following are good choices: Season Summer Morning Great Square of Pegasus Each landmark can be used to locate other stars and/or constellations.

(Note: Orion is a constellation; however the Big Dipper, the Summer Triangle and the Great Square of Pegasus are asterisms. The indicated times are not the only times these landmarks are visible; for example the Big Dipper is circumpolar from most Northern Hemisphere locations, it is visible at all times. However spring evenings and winter mornings are the best time to use the Big Dipper as a landmark.) As you learn the constellations, watch out for asterisms that look similar to constellations; if you are not careful you will find the sky filled with “big dippers” or “great squares.” Try not to go by shape alone. For more information on using landmarks to locate constellations, go to Introduction to the Constellations . To obtain the Abrams Planetarium Sky Calendar, go to Abrams Planetarium (Michigan State University). The Planets Venus, Mars, Jupiter and Saturn are easy to observe with the unaided eye. Each planet is visible within a fixed schedule. For a given evening, each planet may be visible the entire evening, just part of the evening or not be visible at all.

This schedule doesn’t change by much over the course of an evening or two, but will change over a period of weeks or months. Over the course of the year, each of these planets will be visible at least part of the time. It is not possible to see any detail on these planets without a telescope. Whenever Venus is visible, it is much brighter than anything in the sky with the exception of the sun and moon. Mercury, Mars, Jupiter and Saturn are brighter than anything other than Venus, each other, the sun or moon, Sirius and Canopus. There are several things you can notice if you observe planets over an extended period of time. Some planets display noticeable changes in brightness over the course of time. This is particularly true of Mars: sometimes it is almost as bright as Venus but can get as dim as magnitude +2. When Mars is bright, it is bright red; when it is dim, it is a pale pink (at such times it may be difficult to see any color at all). Mars goes from bright to dim back to bright every two years. Changes can be observed in the other planets, but they are less obvious.

All planets move relative to the background stars, but Mars, Jupiter and Saturn will occasionally appear to go into “retrograde” motion (they normally move in a preferred direction, but occasionally they reverse direction, move in that direction for a time, reverse direction again and move in their preferred direction). While Mars, Jupiter and Saturn all have satellites (moons), only the four brightest satellites of Jupiter are bright enough to be seen with the unaided eye. However even these satellites are almost impossible to observe in practice (without binoculars or a telescope) since they almost always get lost in Jupiter’s glare. To observe Mercury, you must plan ahead. The best opportunity to observe Mercury is when it is close to maximum elongation (that is, the planet appears at its highest point in the sky). It also helps to observe from a location without obstructions (such as buildings, trees, hills or mountains) in the direction of the sun. Given the right conditions Mercury will be very bright and can be seen with the naked eye. When Mercury is visible, you have only a short period of time to observe it. Sometimes Mercury is visible in the evening.

In this case you can start observing Mercury shortly after sunset but you will have less than an hour until the planet sets below the horizon. At other times Mercury is visible in the morning. You will be able to see Mercury at most an hour or so before sun rise and can observe it until the light from the rising sun drowns it out. Note: the amount of time that Mercury is visible depends on the position of Mercury in its orbit, the elongation and your horizon; Mercury may be visible for only a few minutes or may not be visible at all if your horizon is poor. Both Venus and Mercury occasionally pass between the Earth and the Sun, such an event is called a transit (for more information on transits, see the next section “The Sun”). Uranus is bright enough to be seen with the unaided eye, but appears as a dot of light that can be very difficult to distinguish from nearby stars. Neptune and Pluto are too dim to be seen with the naked eye. On occasion a planet passes in front of a star or the moon passes in front of a planet, such an event is called an occultation. Occultations can be predicted in advance and are easy to observe if you plan ahead.

Note, the timing of an occultation depends on your exact location. A given occultation is visible from some locations on the earth and not from others. It is often possible to see planets during the daytime. The trick is to know exactly when and where to look. Venus is the easiest to locate, other planets are harder. For more information: Information about occultations can be found at the International Occultation Timing Association. The Sun Several solar phenomena are visible with the naked eye. WARNING: it can be dangerous to observe the phenomena described in this section. If you do not have proper eye protection you may suffer permanent eye damage. It is safe to observe the sun at sunrise and sunset provided you do so without magnification. However observing the sun with binoculars or telescopes is especially dangerous, this can damage your eyes and your binoculars/telescope. This is true even at sunrise/sunset. Sunglasses and smoked glass are not adequate protection. These phenomena include sunspots, solar eclipses and Venus transits (a transit is where a planet passes between the sun and the earth, the planet can be seen as a black dot on the sun’s disk). Observing sunspots is relatively easy.

During solar maximum, which occurs once every 11 years, sunspots are usually quite numerous. At such times, if you have proper eye protection, it is possible to see sunspots (no magnification is needed). (Eye protection is unnecessary at sunrise/sunset provided you use no magnification). At solar minimum (which also occurs every 11 years), there are generally very few sunspots visible. Observing a solar eclipse requires planning ahead. Eclipses occur infrequently: in a given year there may be as few as two solar eclipses or as many as five. A given eclipse is visible only in some parts of the world. Some solar eclipses are partial (the moon covers only part of the sun’s disk) and others are total (the moon covers the sun’s entire disk). If a solar eclipse is total, totality can only be observed for locations on the earth within a narrow band which is at most 170 miles or 270 kilometers wide but thousands of miles/kilometers long. Outside this zone a total eclipse appears as a partial eclipse; the non-total parts of a total eclipse and partial eclipses are often visible from over half the surface of the earth (assuming there are no clouds).

Totality can last as long as seven and one half minutes, but is usually shorter (and the duration varies depending on your exact location). Observing solar eclipses is more dangerous than observing other solar phenomena. It is safe to look at the sun during totality, but you must either look away or put on eye protection the moment totality ends. You normally have a strong reflex reaction which prevents you from looking at the sun for any period of time, however this reflex does not operate during an eclipse, this is the reason people suffer blindness during an eclipse. Transits of Venus occur either once or twice every 121 and a half years. If there are two transits in this period of time, those two transits are eight years apart. That is the case during the 21st century: the last one was on June 8, 2004 and the next one willl be on June 6, 2012. If you have proper eye protection, you can see the disk of Venus without magnification. A Venus transit can last as long as 7.9 hours.

Such a transit will be partially visible from well over half of the planet earth, but the complete transit is visible from only about one third of the globe. However most Venus transits do not last that long and are visible over a smaller area (the duration of the transit varies depending on the location you observe from). For more information see . Transits of Mercury are more common than transits of Venus: Mercury transits occur on average every eight years (though the pattern is not regular). However Mercury’s disk during a transit is too small to be seen with the unaided eye (you must use a telescope with a proper solar filter). A number of phenomena are created by light from the sun interacting with the atmosphere. These phenomena include rainbows, haloes, solar pillars, crepuscular rays, coronas, sundogs, glories and the green flash. Observing the green flash is safe as long as you look at sun only while it is red; observing rainbows is always safe; observing halos, solar pillars, crepuscular rays, coronas and sun glories is safe as long as you make a reasonable effort to avoid looking directly at the sun. Never point binoculars or a telescope directly at the sun even during sunrise or sunset.

For more information: NASA: Solar Eclipse Home Page. The Moon The first thing you will notice about the moon is that it changes phase over the course of its 29 1/2-day cycle. The phases are listed below (this shows the number of days into the cycle and the period of time during which the moon is visible. These times are approximate and do not take into account daylight savings time or variations due to longitude). 1 day Waning Crescent 2 AM to 4 PM You will note the moon is visible during daytime hours a significant fraction of the time. The crescent moon points to the position of the sun (except during the new moon, when the moon is not visible, and during the full moon, when there is no crescent). The moon often appears to point slightly above or below the sun, but this is an optical illusion - it really does point to the sun. You may have heard that the same part of the moon always points to the earth and half the moon can never be seen. This is only partly true; due to a phenomenon called libration you can see 59 of the moon provided you observe over a period of time.

The moon wobbles very slowly when it orbits the earth, and this wobble is noticeable if you compare the edge of the moon day after day for a month or so. With even a causal look at the moon, you can see maria (which are lowlands and dark colored), terrae (which are highlands and light colored) and the terminator (the line between the dark part and the lit part of the moon). Features that are harder to see include craters and mountain ranges. Despite what you might think, the full moon is not the best time to look for lunar features; maria and terrae are easiest to see during the full moon, but craters and other features are easier to see when the sun is low in the lunar sky as seen by that feature. In other words it is best to observe the moon at several different phases (particularly first quarter and last quarter). Lunar craters are too small to be seen without optical aid, however there is one mountain range that can be seen with the naked eye. If you look just after first quarter, the mountain range Apennines can be seen as irregular section of the terminator (which is normally a smooth arc).

Lunar eclipses occur when the Earth passes between the Sun and the Moon. In a given year there may be as few as two lunar eclipses or as many as five; some of these are partial eclipses and some are total. An eclipse is divided into three stages, a “penumbral” stage when the moon is only slightly darkened, an “umbral” stage when the moon is very dark and another “penumbral” stage when the moon is again only slightly darkened. In some partial eclipses there is no umbral stage, and the entire eclipse is penumbral. In these situations, the eclipse is easy to miss. A Lunar Eclipse can last as long as one and three quarters hour, but are usually shorter. On occasion the moon passes in front of a planet or a star, such an event is called an occultation. Occultations can be predicted in advance and are easy to observe if you plan ahead. Note, the timing of an occultation depends on your exact location. A given occultation is visible from some locations on the earth and not from others. For more information: The International Occultation Timing Association gives information about lunar occultations.

Asteroids Asteroids are small bodies, most of which are in orbits between Mars and Jupiter. All are faint. The best time to observe an asteroid is when it is at opposition (that is the time it is closest to the earth). If it is visible at all, an asteroid will be visible only as a dot of light that is difficult to distinguish from nearby stars. Of the hundreds of known asteroids, Vesta is the easiest to observe and will sometimes be visible to the naked eye. Experienced observers at very dark sites may be able to see asteroids in addition to Vesta. For more information see the IAU: Minor Planet Center. This site describes many asteroids that are not naked eye visible, pay attention to the magnitudes listed on this site. Comets Some comets are short-period comets, that is they return after a set period, which can be as short as three years or as long as 200 years (any comet with a period longer than 200 years is not considered to be short-period). The best known of these comets is Comet Haley, which returns every 76 years. Many short-period comets are known, but not all comets are short-period. New comets are continually being discovered.

Most newly discovered comets are not short-period; they will not return for hundreds or thousands of years. Comets generally spend most of their time far away from the sun. They are close to the sun for a relatively short time, but this is the only time they are easy to observe. New comets are often detected far from the sun (when they are quite dim). Usually such comets are getting closer to the sun, if so they can be expected to get brighter over time. Astronomers often make predictions about how much brighter these comets will get, but such predictions are frequently wrong (Comet Kohoutek in 1973 was much dimmer than predicted, Comet West in 1975 was much brighter than predicted). At any point in time, over a dozen comets can be seen through telescopes; however most are not naked eye visible. Comets that have bright easily visible tails occur roughly once every 10 years, comets that are naked eye visible with small fuzzy tails are somewhat more common. Comets have at least two tails, a dust tail and an ion tail; the dust tail is the easiest to see, the ion tail is visible only in some very bright comets.

When it is visible, the ion tail is oriented at a slight angle to the dust tail and is blue in color. For a list of comets that are currently visible, see IAU: Astronomical Headlines. Note, most of the comets listed on this page are too dim to be seen without optical aid; pay attention to the magnitudes of the listed comets. Interplanetary Dust Dust within the solar system can reflect light from the sun, and this reflected light can be seen from a dark site. Zodiacal light is a soft glow that is usually triangular in shape. There are two areas of zodiacal light, one in the east and one in the west; they are easier to see in winter. The zodiacal band is a band of light that joins the two areas of zodiacal light, but it is very difficult to see. An oval shaped section of the zodiacal band, the Gegenshein often is bright enough to be seen even when the zodiacal band itself cannot be seen. Aurorae Aurorae are bright lights visible at night caused by electrons entering the earth’s upper atmosphere.

Aurorae in the Northern Hemisphere are called Aurorae Borealis or Northern Lights; aurorae in the Southern Hemisphere are called Aurorae Australis or Southern Lights. Aurorae are more frequent within an oval about 2,500 kilometers wide centered on the North Magnetic Pole (located in Northern Canada) and within an oval about 2,500 kilometers wide centered on the South Magnetic Pole (located in the ocean near Antarctica). This means the Aurorae Borealis is most commonly seen from Alaska, Canada, Greenland and Iceland. It can be seen, but less frequently from the northern continental United States, Scandinavia, Ireland and the United Kingdom. On rare occasions, aurora have been seen even further from the north magnetic pole. The Aurorae Australis is rarely seen since there are no populated areas near the South Magnetic Pole. Aurora are more common at solar maximum (which occurs every 11 years). Aurora can be relatively common up to 3 years after the solar maximum. Scientists have been somewhat successful (but not perfect) at predicting when aurorae will occur.

Aurorae can appear in several different shapes, but the most common shapes have been described as sheets, curtains and streamers. They can appear in different colors (green is the most common, however red, violet and blue have been observed). Under unusual conditions, aurora can appear to pulse on and off over a large section of the sky (the author has observed this only once). Aurorae observing does not require dark skies, but colors and pulsation are subtle phenomena which are easier to observe if you are dark adapted and observing from a dark site. For more information, see The International Meteor Organization. Artificial Satellites There are thousands of man-made satellites in orbit around the earth. Some are too dim to be seen with the unaided eye. However others can easily be seen if you know when and where to look. In a given evening, you can expect to see several satellites; they appear as dots of light that slowly move across the sky. For more information see “What Satellite is That?” by Christopher Sarnecki, June, 1999. Galaxies The universe is composed of billions of galaxies.

If you go outside at night, almost all the objects you can see with the unaided eye are within our own Milky Way galaxy. There are four exceptions: M31, The Andromeda Galaxy - Easy to see from a relatively dark site. The Large Magellanic Cloud - Easy to see, but only from the Southern Hemisphere. The Small Magellanic Cloud - Easy to see, but only from the Southern Hemisphere. M33, The Triangulum Galaxy - Few naked eye observations have been reported, most from experienced observers at very dark sites. M33 is very difficult to see without optical aid. Our Galaxy, the Milky Way, can be seen from any reasonably dark site as a band of light that extends across the sky. Stars In general all stars vary slightly in brightness over time. Most of these changes are insignificant, however some stars vary noticeably in brightness. The majority of these so-called variable stars change in brightness over a period somewhere between a few hours and a year. A few such stars can be seen with the naked eye; if one is careful, persistent and patient, it is possible to track the variations of these stars.

In some cases the star is visible during part of its range and not visible during the rest of its range. Two types of variable stars, novae and supernovae, change brightness dramatically and unpredictably. Novae will increase in brightness from 7 to 16 magnitudes over a day or two and then decrease in brightness slowly over the next several months. Novae bright enough to be seen with the naked eye occur once every few years. Supernovae increase in brightness over 20 magnitudes in the span of a few days and then decline slowly over the next few years. Bright supernovae are rare. Over the past 400 years, there have been only three naked eye supernovae, one in the year 1604, one in 1885 and one in 1987. Both novae and supernovae are unpredictable. It is possible to locate a previously undiscovered novae or supernovae with persistence and luck. The color of stars is easily observed. Color is directly related to the star’s temperature. The coldest stars are red; the hottest stars are blue-white. Stars with intermediate temperatures can be orange, yellow or white.

It is easy to tell the color of bright stars, but difficult to tell the color of the dimmer stars (dim stars often appear white even though they may be red or blue or some other color). Many of the points of light that appear to be stars are in fact double stars or even triple or quadruple stars. In a few cases, it is possible to “split” these stars (that is observe the different components) with the naked eye. In some cases, stars can be found in large groups called “clusters.” There are two types of clusters, globular and open. There are a few globular clusters and a few open clusters visible with the naked eye (they include Omega Centauri, M13 and the Pleiades). In addition, stars can be grouped into either associations or streams these are stars that are loosely bound but are gradually moving away from each other. Many associations and streams are visible, however it is not always easy to tell which stars are included and which are not. Two of the most obvious associations involve some of the brightest stars in Ursa Major and Orion. For more information: The American Association of Variable Star Observers posts information about variable stars and lists of newly discovered novae.

Stars listed with magnitudes greater than 6.5 will be difficult to see with the naked eye. For a list of naked eye double stars, see “Observing Naked (or I got 5.5 arcmins resolution),” by Christopher Sarnecki, October, 1999 (in part) and January 2000 (in part) and “Amateur Astronomer Makes Record Double Star Split,” by Christopher Sarnecki, August, 2000. Nebulae Nebulae are areas of gas within the galaxy. Some nebulae (emission, reflection and planetary nebulae) either glow or reflect light from nearby stars; many such nebulae can be seen from the earth. Other nebulae (dark nebulae) do not glow, but can be detected because stars cannot be seen through them (these nebulae are opaque and starlight cannot pass through them). A few nebulae are visible to the unaided eye, they include: The Orion Nebula. For more information see The National Deep Sky Observers Society (Observing the Deep Sky with the Naked Eye).

Night Myopia Many people suffer from near-sightedness or myopia, and they correct for it with eyeglasses or contact lenses. It has been known for some time that myopia often gets worse when observing at night. This is called night myopia. It’s not a serious condition, and most people don’t realize they have it. It’s temporary and goes away during the daytime. However if you suffer from this condition, your night visible isn’t quite as good as it could be and you may not be able to see some of the objects described earlier in this article. If you use a telescope or binoculars, the focus knob will allow you to compensate for night myopia. However this doesn’t work for naked eye observing. The first step is to determine if this situation applies to you (each person’s eyes are different). There is a company that sells a “night myopia flipper” set. These are lens that you can place over your eyeglasses (or contact lens) and determine if additional correction is necessary to deal with night myopia. Take the flipper set and wait until your eyes are dark adapted. Then use trail and error to find out which correction (if any) works best.

Warning, if you are not careful you may end up with an improper correction and this can lead to headaches. Take your time, may sure you allow your eyes to adjust. To order a set, go to . (Look for the “Night Myopia Diagnostic Flippers.”) If you think correction is appropriate, you should discuss the situation with your eye care professional. Remember this may require the purchase of eyeglasses that will only be useful for naked eye nighttime observing; such eyeglasses are not necessary for binocular or telescope viewing. Whether such a purchase is worth the expense needs to be an individual decision. For more information there is an article in Sky and Telescope magazine. See Joshua Roth. September 2005. “Special Report: Night Myopia.” Sky and Telescope. Vol 110, Number 3. Photography What is Aurora? What is Aurora? Aurora Aurora (astronomy) – Coloured light in the night sky near the Earth’s magnetic poles, called aurora borealis (‘northern lights’) in the northern hemisphere and aurora australis (‘southern lights’) in the southern hemisphere.

Although auroras are usually restricted to the polar skies, fluctuations in the solar wind occasionally cause them to be visible at lower latitudes. An aurora is usually in the form of a luminous arch with its apex towards the magnetic pole, followed by arcs, bands, rays, curtains, and coronae, usually green but often showing shades of blue and red, and sometimes yellow or white. Auroras are caused at heights of over 100 km/60 mi by a fast stream of charged particles from solar flares and low-density ‘holes’ in the Sun’s corona. These are guided by the Earth’s magnetic field towards the north and south magnetic poles, where they enter the upper atmosphere and bombard the gases in the atmosphere, causing them to emit visible light. Northern lights is the name of a light phenomenon often seen in the northern regions. The lights have been around since Earth formed an atmosphere -the dinosaurs saw it, early humans saw it and our descendants will se it. The scientific name for the phenomenon is “Aurora Borealis”, aurora for short.

Aurora australis, Invercargill This photograph of the southern lights or aurora australis, most commonly seen in southern New Zealand, was taken in September 2002 from Invercargill. It shows a typical red and green aurora, the nearly vertical rays tracing the earth’s magnetic field lines. The M?ori name for Stewart Island, at the south of the South Island, is Rakiura, which means ‘glowing skies’. This may allude to the aurora australis, or simply to the dramatic southern sunsets. Aurora from Space From space, the aurora is a crown of light that circles each of Earth’s poles. The IMAGE (below) satellite captured this view of the aurora australis (southern lights) on September 11, 2005, four days after a record-setting solar flare sent plasma—an ionized gas of protons and electrons—flying towards the Earth. The ring of light that the solar storm generated over Antarctica glows green in the ultraviolet part of the spectrum, shown in this image. The IMAGE observations of the aurora are overlaid onto NASA’s satellite-based Blue Marble image.

From the Earth’s surface, the ring would appear as a curtain of light shimmering across the night sky. An aurora (plural aurorae/auroras) is an electro-static phenomenon, characterised by a bright glow and caused by the collision of charged particles in the magnetosphere with atoms in the Earth’s upper atmosphere. An aurora is usually observed in the night sky, particularly in the polar zone. For this latter reason, some scientists call it a “polar aurora” (or “aurora polaris”). In northern latitudes, it is known as the aurora borealis, which is named after the Roman goddess of the dawn, Aurora, and the Greek name for north wind, Boreas. Especially in Europe, it often appears as a reddish glow on the northern horizon, as if the sun were rising from an unusual direction. The aurora borealis is also called the northern lights since it is only visible in the North sky from the Northern Hemisphere. The aurora borealis most often occurs from September to October and from March to April. Its southern counterpart, aurora australis, has similar properties. Australis is the Latin word for “of the South”.

The Aurora Australis as seen from the Space Shuttle Discovery on STS-39. The payload bay and tail of Discovery can be seen on the left hand side of the picture. Auroras are caused when high-energy electrons pour down from the Earth’s magnetosphere and collide with atoms. Red aurora occurs from 200 km to as high as 500 km altitude and is caused by the emission of 6300 Angstrom wavelength light from oxygen atoms. Green aurora occurs from about 100 km to 250 km altitude and is caused by the emission of 5577 Angstrom wavelength light from oxygen atoms. The light is emitted when the atoms return to their original unexcited state. NASA-Johnson Space Center: “The Gateway to Astronaut Photography of Earth.” Aurora Australis Observed From the International Space Station Among the views of Earth afforded astronauts aboard the International Space Station (ISS), surely one of the most spectacular is of the aurora.

These ever-shifting displays of colored ribbons, curtains, rays, and spots are most visible near the North (aurora borealis) and South (aurora australis) Poles as charged particles (ions) streaming from the Sun (the solar wind) interact with Earth’s magnetic field. While aurora are generally only visible close to the poles, severe magnetic storms impacting the Earth’s magnetic field can shift them towards the equator. This striking aurora image was taken during a geomagnetic storm that was most likely caused by a coronal mass ejection from the Sun on May 24, 2010. The ISS was located over the Southern Indian Ocean at an altitude of 350 kilometers (220 miles), with the astronaut observer most likely looking towards Antarctica (not visible) and the South Pole. The aurora has a sinuous ribbon shape that separates into discrete spots near the lower right corner of the image. While the dominant coloration of the aurora is green, there are faint suggestions of red left of image center. Dense cloud cover is dimly visible below the aurora.

The curvature of the Earth’s horizon (the limb) is clearly visible, as is the faint blue line of the upper atmosphere directly above it (at image top center). Several stars appear as bright pinpoints against the blackness of space at image top right. Auroras happen when ions in the solar wind collide with atoms of oxygen and nitrogen in the upper atmosphere. The atoms are excited by these collisions, and they typically emit light as they return to their original energy level. The light creates the aurora that we see. The most commonly observed color of aurora is green, caused by light emitted by excited oxygen atoms at wavelengths centered at 0.558 micrometers, or millionths of a meter. (Visible light is reflected from healthy (green) plant leaves at approximately the same wavelength.) Red aurora are generated by light emitted at a longer wavelength (0.630 micrometers), and other colors such as blue and purple are also sometimes observed. What causes the showers of charged particles that create the northern lights? Ultimately, the source lies in the solar wind, a fast-moving stream of particles constantly flowing from the Sun that carries the Sun’s magnetic field out into space.

The solar wind, typically moving at 250 miles (400 kilometers) per second, flows past Earth’s magnetic field and molds it into an elongated bubble or cavity, compressing its sunward side and stretching its night side far beyond the Moon’s orbit. Under certain conditions, the solar wind’s magnetic field can merge with Earth’s, creating electrical currents that drive protons and electrons into the polar atmosphere. Powerful events occurring on the Sun can drive enormous changes in the solar wind, increasing both its speed and density and enhancing its effect on Earth. Understanding just how Earth’s magnetic field responds to such events is now a focus of much solar and space research. We are increasingly dependent on technologies that are extremely sensitive to changes in the space environment, changes often collectively referred to as “space weather.” The story of Galaxy 4, a heavily used communications satellite, serves as a good example. At 22h UT on May 19, 1998, while in geostationary orbit above the central United States, Galaxy 4 lost its primary and backup attitude control systems. At the time, Galaxy 4 handled about 80 percent of all U.S. pager traffic.

Controllers could no longer maintain a stable link between the satellite and Earth, resulting in a loss of pager service to an estimated 45 million customers. Researchers believe the incident occurred because a sequence of solar events about two weeks prior to the failure created an extremely energetic cloud of electrons that wreaked havoc with the satellite. The Northern Lights - where, when and what. The Northern Lights - where, when and what. By Truls Lynne Hansen Tromsø Geophysical Observatory - University of Tromsø. Where can we see the northern lights? The Northern Lights, as the name suggests, are especially related to the polar regions. They occur most frequently in a belt of radius 2500 km centered on the magnetic north pole. This so-called auroral zone extends over northern Scandinavia, Island, the southern tip of Greenland and continuing over northern Canada, Alaska and along the northern coast of Siberia. The coasts of the Norwegian counties of Troms and Finnmark lay where occurrence is greatest, making northern Norway, due to its ease of access and mild winter climate, an attractive destination for people interested in observing this atmospheric phenomenon. The Northern Lights can be seen from regions both north and south of the auroral zone, but the likelihood decreases with distance.

There is a corresponding auroral zone around the southern magnetic pole, but these 'Southern Lights' are largely only seen from Antarctica and the surrounding ocean. Of the populated regions in the southern hemisphere, the Southern Lights, may only be glimpsed from Tasmania and southern New Zealand. The Northern and Southern Lights occur simultaneously and are almost mirror images of each other. How often can you see the Northern Lights? In Troms and Finnmark, we can see the Northern Lights every other clear night, if not even more frequently. From southern Norway, sightings would be only a few times a month while in central Europe hardly more than a few times a year and they have even been seen from the Mediterranean but only a few times each century. To the north of the auroral zone, on Spitzbergen, the Northern Lights are a common sight, although they don't appear as often as in northern Norway. When can we see the Northern Lights? We associate the Northern Lights with wintertime, although in reality they are present the year round; it's just that we can't see them when the nights are light as the background sky has to be fairly dark.

In practice, in northern Norway we are restricted to the period starting at the beginning of September and extending until the middle of April. On the other hand, if the Northern Lights are strong enough, they may still be seen against a twilight sky, and it is not unusual to see them from Tromsø on an August evening. The Northern Lights are often referred to as 'night aurora' because they occur on the night side of the Earth and they commonly appear in the early evening and continue late into the night. Although this is the most usual form of aurora, during winter on Spitzbergen, where it is dark even at midday, it is possible to observe the rarer 'day aurora' which occurs on the 'day side' of the Earth. The aurora lies well above the highest clouds, so we need clear skies to be able to see it. In fact, cloudy skies are the greatest obstacle for auroral observations in northern Norway and for this reason the inland regions are better suited than near the coast. The days around full moon are not conducive to viewing the Northern Lights because the background sky becomes so light. Finally, one should avoid cities and areas with much street lighting in order to experience the Northern Lights to the full.

How high up are the Northern Lights? Most aurorae occur between 90 and 130 km above sea level, but some, particularly the ray-like forms, extend to several hundred kilometers up. In comparison, the usual altitude for a jet aircraft is around 10km and the ozone layer lies between 20 and 30km so we have to be almost up at the heights of satellites orbits to be at the same height as the aurora. A consequence of its great height is that the aurora is visible at horizontal distances of several hundred kilometers. Thus an aurora over Bear Island will be visible from both Spitzbergen and Tromsø, and one over Tromsø can be seen in the northern sky from central Norway. What exactly are the Northern Lights? The Northern Lights stem from when large numbers of electrically charged particles (electrons) at high speed stream in towards the Earth along its magnetic field and collide with the highest air particles. The air then lights up rather like what happens in a fluorescent light tube. The resulting colours reflect which gases we find up there, the most usual yellow-green colour coming from oxygen. Red colouring is also due to oxygen with a contribution from nitrogen.

The violet we often see at the lower edge of the aurora is due to nitrogen, as is most blue colouring. The charged particles originate from the sun, and it is the 'weather' conditions on the sun that decide whether or not we will see the aurora. Particles can stream out from the sun and some are captured by the Earth's magnetic field and find their way into the polar regions. On the way, they travel out into the night side of the Earth and gain extra energy - we still lack understanding of exactly what happens out there! The Mooney Show, Saturday November 21st 2015 - The Mooney Show - RTÉ Radio 1 Podcasts The Mooney Show, Saturday November 21st 2015 *** IF YOU WOULD LIKE TO TAKE PART IN OUR GENERAL KNOWLEDGE QUIZ, SIMPLY E-MAIL YOUR NAME AND CONTACT NUMBER TO MOONEY@RTE.IE !*** Follow us on Twitter - @rtemooney ! E-mail mooney@rte.ie if you'd like to win a hotel break in our general knowledge quiz! On The Mooney Show this evening...

We've live music from the Vard Sisters, Evelyn Cusack tells us why we've been having such mixed weather of late, and three players attempt to beat the clock, and each other, to win a two-night break to the Castleknock Hotel & Country Club in Dublin... Share: Weird Weather The November weather has been weird, hasn't it? At the beginning of the month, there was an article on the BBC website to say that temperatures had soared up to 22.4° in Wales on Sunday, November 1st. Now that might seem a distant memory, but they were amongst the highest November temperatures since records began! A distant memory for sure. Because when the weather changed, it changed radically! Even at the beginning of the month, Met Eireann had already released a list of names for storms, as they took hold. Abigail was the first. Then came Barney. What's next? To tell us more, we're joined in studio by weather forecaster Evelyn Cusack... To read more of the Weather reports from the future, as mentioned by Evelyn, visit . Share: Mooney's Saturday Quiz We started our quiz a few weeks ago and WOW...! It seems to have struck a real chord with listeners.

So, we figured, if you're onto a good thing, why change!? It's quiz time AGAIN today. And this time, we are going to take somebody up to the capital, to the luxurious Castleknock Hotel & Country Club in Dublin! Castleknock Hotel & Country Club is an award-winning 4-star hotel set in beautiful grounds with its own golf course, right on the doorstep of Dublin city. The hotel is a quick drive from Dublin city centre but feels like a world away from the bustle of the city. There’s an 18-hole golf course, a deluxe spa, a well-equipped leisure centre, award-winning restaurants and great bars, including the newly launched "The Avenue" Bar. Our quiz winner today will enjoy a two night break for two people including breakfast on both mornings, and an evening meal for two in the award-winning Park Restaurant and can also enjoy full use of the hotel’s leisure facilities throughout your stay. Quiz Questions (audio rounds excluded!) Player 1 - Questions 1. Beginning with the letter ‘H’, what common term refers to the amount of water vapour that is held in the air? 2.

What's the more exotic name of the 'Northern Lights' visible under certain conditions in the Northern Hemisphere night sky? 3. Beginning with the letter "M", a scientist who studies weather is called what? 4. In 1983, the Weather Girls had a huge disco hit with the song, It's Raining... what? 5. The city of Chicago is also known by which weather-related name? 6. What is the childlike name given to the significant weather activity linked to sea temperature rise in the Pacific Ocean? 7. The area of central USA that features many tornadoes is known as Tornado _______? Player 2 - Questions 1. What the weather-related nickname was given to the snooker genius, Jimmy White? 2. What are the narrow bands of strong winds called which move around the world , between about six and twelve miles high? 3. It's a word that also applies to tying ropes. What is the unit of measurement of wind speed? 4. Beginning with the letter K, what was the name of the hurricane that nearly destroyed New Orleans in 2005? 5. What device is used to measure how cold or hot the air temperature is? 6.

Around 1723, Italian composer Antonio Vivaldi composed a group of violin concertos called The Four... what? 7. What country experiences the most tornadoes? Hint: think The Wizard Of Oz! Player 3 - Questions 1. In 1973, Elton John sang a song about Marilyn Monroe entitled Candle In The... what? 2. Beginning with the letter ‘O’, what layer shields the Earth from harmful ultraviolet radiation that comes from the sun? 3. What’s the name of the circulating Atlantic ocean current which warms Western Europe? 4. What weather-related nickname was given to the snooker genius, Alex Higgins? 5. What type of weather phenomenon is a Sirocco? 6. It was a movie and an album released in 1984 by Prince. And it was called Purple ... what? 7. Beginning with the letter "F”, the practice of attempting to predict the weather is known as weather _______? 8. In Ireland, St. Valentine’s Day occurs during which season? 9. in 1983, Katrina and the Waves sang about walking on what? 10. What is the name of a weather instrument used to measure atmospheric pressure?

Player 1 - Questions and Answers 1. Beginning with the letter ‘H’, what common term refers to the amount of water vapour that is held in the air? (Humidity) 2. What's the more exotic name of the 'Northern Lights' visible under certain conditions in the Northern Hemisphere night sky? (Aurora Borealis) 3. Beginning with the letter "M", a scientist who studies weather is called what? (Meteorologist) 4. In 1983, the Weather Girls had a huge disco hit with the song, It's Raining... what? (Men) 5. The city of Chicago is also known by which weather-related name? (The Windy city). 6. What is the childlike name given to the significant weather activity linked to sea temperature rise in the Pacific Ocean? (El Nino) 7. The area of central USA that features many tornadoes is known as Tornado _______? (Alley) Player 2 - Questions and Answers 1. What the weather-related nickname was given to the snooker genius, Jimmy White? (Whirlwind) 2.

What are the narrow bands of strong winds called which move around the world , between about six and twelve miles high? (Jet Streams) 3. It's a word that also applies to tying ropes. What is the unit of measurement of wind speed? (Knot) 4. Beginning with the letter K, what was the name of the hurricane that nearly destroyed New Orleans in 2005? (Katrina.) 5. What device is used to measure how cold or hot the air temperature is? (Thermometer) 6. Around 1723, Italian composer Antonio Vivaldi composed a group of violin concertos called The Four... what? (Seasons) 7. What country experiences the most tornadoes? Hint: think the Wizard of Oz! (USA) Player 3 - Questions and Answers 1. In 1973, Elton John sang a song about Marilyn Monroe entitled Candle In The... what? (Wind) 2. Beginning with the letter ‘O’, what layer shields the Earth from harmful ultraviolet radiation that comes from the sun. (ozone) 3. What’s the name of the circulating Atlantic ocean current which warms Western Europe? (The Gulf Stream) 4.

What weather-related nickname was given to the snooker genius, Alex Higgins? (Hurricane) 5. What type of weather phenomenon is a Sirocco? (wind) 6. It was a movie and an album released in 1984 by Prince. And it was called Purple… what? (Rain) 7. Beginning with the letter "F”, the practice of attempting to predict the weather is known as weather _______? (Forecasting) 8. In Ireland, St. Valentine’s Day occurs during which season? (Winter) Feb 14th 9. in 1983, Katrina and the Waves sang about walking on what? (Sunshine) 10. What is the name of a weather instrument used to measure atmospheric pressure? (Barometer) Share: The Vard Sisters It's amazing how pieces of music have different connotations for different generations. If you were a TV viewer in 1997, anywhere in the UK or Ireland, you would most likely have associated that piece of music with one particular airline. The piece is called The Flower Duet.

It's taken from the opera Lakmé, by Delibe - and years before "the world's favourite airline" commandeered the tune, it had been a staple in the repertoire of a certain trio of sisters from South Dublin. They were Cathy, Wendy and Lisa - The Vard Sisters. Derek with The Vards Well, British Airways might have felt a certain ownership over the tune. But in 1998, having performed it since their childhood years, the three Vard Sisters released The Flower Duet as the lead track on their debut album, Heavenly. The rest is history. Heavenly became one of the bestselling debut Irish albums of all time. It was a sublime collection of tunes the girls had long-performed at weddings, funerals, corporate functions, concert venues. The Vards with Derek Mooney & Evelyn Cusack Now, 17 years later, they have just released Heavenly Too. And we're delighted that Cathy, Wendy and Lisa join us in studio this evening for a chat and to perform Somewhere Over The Rainbow. For more information about The Vard Sisters, visit .

Question: What's the more exotic name of the 'Northern Lights' visible under certain conditions in the Northern Hemisphere night sky?
Answer: Aurora Borealis