Why Earth is Closest to Sun in Dead of Winter Why Earth is Closest to Sun in Dead of Winter By Mary Lou Whitehorne, Special to SPACE.com | January 2, 2007 09:00am ET MORE It's winter in the Northern Hemisphere and we're at our closest point to the Sun. Closest? Yes, you read that right. Closest. For northerners, the winter solstice has just passed. But the truth is, on January 3, 2007, Earth reaches perihelion, its closest point to the Sun in its yearly orbit around our star. At first glance, it makes no sense. If Earth is closest to the Sun in January, shouldn't it be summer? Maybe, if you live in the Southern Hemisphere. So what does this mean? Earth's orbit is not a perfect circle. It is elliptical, or slightly oval-shaped. This means there is one point in the orbit where Earth is closest to the Sun, and another where Earth is farthest from the Sun. The closest point occurs in early January, and the far point happens in early July (July 7, 2007).

If this is the mechanism that causes seasons , it makes some sense for the Southern Hemisphere. But, as an explanation for the Northern Hemisphere, it fails miserably. In fact, Earth's elliptical orbit has nothing to do with seasons. The reason for seasons was explained in last month's column , and it has to do with the tilt of Earth's axis. But our non-circular orbit does have an observable effect. It produces, in concert with our tilted axis, the analemma. If you plot the noontime position of the Sun in the sky over a one-year period, it produces a figure-eight shape on the sky (Figure A). This is the analemma . You may have seen it drawn on a globe of Earth. The shape results from the combination of two things: the 23.5° tilt of Earth on its spin axis, and the elliptical shape of Earth's orbit around the Sun. The highest point on the analemma is the Sun's noon position on the summer solstice. The lowest point marks the winter solstice. The difference in the Sun's noontime height in the sky is caused by Earth's tilted axis. What about the left-to-right variation in the analemma's curve?

That's where our elliptical orbit comes in! Look at Figure A again. Notice the vertical line running up from the south point on the horizon? That's the meridian. The meridian runs straight up and over the sky, from due north to due south. If Earth's orbit was a perfect circle, the Sun would cross the meridian at noon every day (ignoring daylight savings time). But our orbit is slightly oval-shaped. In July, we are at our furthest point from the Sun, and Earth moves slower than average along its path. In January, we are closer to the Sun, and Earth speeds up a bit in its orbital progress. The result of this change in speed means the Sun crosses the meridian a little early, or a little late, depending on where Earth is in its orbit. For all points along the curve to the left of the meridian, the Sun is "slow." It crosses the meridian after 12:00 p.m. For all points along the curve to the right of the meridian, the sun is "fast," crossing the meridian slightly before noon. Astronomers call this the equation of time. It is marked on many sundials.

The equation of time is defined as the difference between true solar time (determined by the Sun's position in the sky) and mean solar time (the time told by your watch). The two times can vary by as much as 16 minutes over the course of a year. Earth reaches perihelion on January 3, 2007 (Figure C). The Earth-Sun distance will be 147,093,602 km. Aphelion, the greatest distance from the Sun, occurs on July 7, 2007, when the Earth-Sun distance will be 152,097,053 km. The difference between the two is 5,003,451 km, (3.3 percent), and not enough to cause the seasons. Even though, at this time of year, we're as close to the Sun as we can get, for the Northern Hemisphere, it will always be winter. Happy perihelion!

Solar System Planets: Order of the 8 (or 9) Planets Solar System Planets: Order of the 8 (or 9) Planets By Robert Roy Britt | January 22, 2016 12:35pm ET MORE The planets of the solar system as depicted by a NASA computer illustration. Orbits and sizes are not shown to scale. Credit: NASA Ever since the discovery of Pluto in 1930, kids grew up learning about the nine planets of our solar system. That all changed starting in the late 1990s, when astronomers began to argue about whether Pluto was a planet. In a highly controversial decision , the International Astronomical Union ultimately decided in 2006 to call Pluto a “dwarf planet,” reducing the list of “real planets” in our solar system to eight. However, astronomers are now hunting for another planet in our solar system, a true ninth planet , after evidence of its existence was unveiled on Jan. 20, 2016. The so-called "Planet Nine," as scientists are calling it, is about 10 times the mass of Earth and 5,000 times the mass of Pluto.

[ Solar System Pictures: A Photo Tour ] If you insist on including Pluto , then that world would come after Neptune on the list; Pluto is truly way out there, and on a wildly tilted, elliptical orbit (two of the several reasons it got demoted). Interestingly, Pluto used to be the eighth planet, actually. More on that below. Terrestrial planets The inner four worlds are called “ terrestrial planets ,” because, like Earth, their surfaces are all rocky. Pluto, too, has a solid surface (and a very frozen one) but has never been grouped with the four terrestrials. Jovian planets The four large outer worlds — Jupiter, Saturn, Uranus, and Neptune — are known as the “Jovian planets” (meaning “Jupiter-like”) because they are all huge compared to the terrestrial planets, and because they are gaseous in nature rather than having rocky surfaces (though some or all of them may have solid cores, astronomers say).

According to NASA , "two of the outer planets beyond the orbit of Mars — Jupiter and Saturn — are known as gas giants; the more distant Uranus and Neptune are called ice giants." This is because, while the first two are dominated by gas, while the last two have more ice. All four contain mostly hydrogen and helium. Dwarf planets The IAU definition of a full-fledged planet goes like this: A body that circles the sun without being some other object's satellite, is large enough to be rounded by its own gravity (but not so big that it begins to undergo nuclear fusion, like a star) and has "cleared its neighborhood" of most other orbiting bodies. Yeah, that’s a mouthful. The problem for Pluto, besides its small size and offbeat orbit, is that it shares its space with lots of other objects in the Kuiper Belt , beyond Neptune. Still, the demotion of Pluto remains controversial . The IAU planet definition puts other small, round worlds in the dwarf planet category, including the Kuiper Belt objects Eris , Haumea , and Makemake . Also now a dwarf planet is Ceres , a round object in the Asteroid Belt between Mars and Jupiter.

Ceres was actually considered a planet when discovered in 1801 and then later deemed to be an asteroid. Some astronomers like to consider Ceres as a 10th planet (not to be confused with Nibiru or Planet X ), but that line of thinking opens up the possibility of there being 13 planets, with more bound to be discovered. The planets Below is a brief overview of the eight primary planets in our solar system , in order from the inner solar system outward: Mercury The closest planet to the sun, Mercury is only a bit larger than Earth's moon. Its day side is scorched by the sun and can reach 840 degrees Fahrenheit (450 Celsius), but on the night side, temperatures drop to hundreds of degrees below freezing. Mercury has virtually no atmosphere to absorb meteor impacts, so its surface is pockmarked with craters, just like the moon. Over its four-year mission, NASA's MESSENGER spacecraft has revealed views of the planet that have challenged astronomers' expectations.

Discovery: Known to the ancients and visible to the naked eye Named for: Messenger of the Roman gods Diameter: 3,031 miles (4,878 km) Orbit: 88 Earth days Venus' southern hemisphere, as seen in the ultraviolet. Credit: ESA Venus The second planet from the sun, Venus is terribly hot, even hotter than Mercury. The atmosphere is toxic. The pressure at the surface would crush and kill you. Scientists describe Venus’ situation as a runaway greenhouse effect. Its size and structure are similar to Earth, Venus' thick, toxic atmosphere traps heat in a runaway "greenhouse effect." Oddly, Venus spins slowly in the opposite direction of most planets. The Greeks believed Venus was two different objects — one in the morning sky and another in the evening. Because it is often brighter than any other object in the sky — except for the sun and moon — Venus has generated many UFO reports.

Discovery: Known to the ancients and visible to the naked eye Named for: Roman goddess of love and beauty Diameter: 7,521 miles (12,104 km) Orbit: 225 Earth days An image of the Earth taken by the Russian weather satellite Elektro-L No.1. Credit: NTsOMZ Earth The third planet from the sun, Earth is a waterworld, with two-thirds of the planet covered by ocean. It’s the only world known to harbor life. Earth’s atmosphere is rich in life-sustaining nitrogen and oxygen. Earth's surface rotates about its axis at 1,532 feet per second (467 meters per second) — slightly more than 1,000 mph (1,600 kph) — at the equator. The planet zips around the sun at more than 18 miles per second (29 km per second).

Diameter: 7,926 miles (12,760 km) Orbit: 365.24 days Day: 23 hours, 56 minutes Related: Mars researchers are focusing both Earth-based and planet orbiting sensors to better understand sources of methane on the red planet. Image Credit: Space Telescope Science Institute Mars The fourth planet from the sun, is a cold, dusty place. The dust, an iron oxide, gives the planet its reddish cast. Mars shares similarities with Earth: It is rocky, has mountains and valleys, and storm systems ranging from localized tornado-like dust devils to planet-engulfing dust storms. It snows on Mars. And Mars harbors water ice. Scientists think it was once wet and warm, though today it’s cold and desert-like. Mars' atmosphere is too thin for liquid water to exist on the surface for any length of time. Scientists think ancient Mars would have had the conditions to support life, and there is hope that signs of past life — possibly even present biology — may exist on the Red Planet.

Discovery: Known to the ancients and visible to the naked eye Named for: Roman god of war Diameter: 4,217 miles (6,787 km) Orbit: 687 Earth days Day: Just more than one Earth day (24 hours, 37 minutes) Related: Close-up of Jupiter's Great Red Spot as seen by a Voyager spacecraft. Credit: NASA/JPL-Caltech Jupiter The fifth planet from the sun, Jupiter is huge and is the most massive planet in our solar system. It’s a mostly gaseous world, mostly hydrogen and helium. Its swirling clouds are colorful due to different types of trace gases. A big feature is the Great Red Spot, a giant storm which has raged for hundreds of years. Jupiter has a strong magnetic field, and with dozens of moons, it looks a bit like a miniature solar system.

Discovery: Known to the ancients and visible to the naked eye Named for: Ruler of the Roman gods Diameter: 86,881 miles (139,822 km) Orbit: 11.9 Earth years The shadow of Saturn's moon Mimas dips onto the planet's rings and straddles the Cassini Division in this natural color image taken as Saturn approaches its August 2009 equinox. Credit: NASA/JPL/Space Science Institute Saturn The sixth planet from the sun is known most for its rings . When Galileo Galilei first studied Saturn in the early 1600s, he thought it was an object with three parts. Not knowing he was seeing a planet with rings, the stumped astronomer entered a small drawing — a symbol with one large circle and two smaller ones — in his notebook, as a noun in a sentence describing his discovery. More than 40 years later, Christiaan Huygens proposed that they were rings. The rings are made of ice and rock. Scientists are not yet sure how they formed. The gaseous planet is mostly hydrogen and helium. It has numerous moons .

Discovery: Known to the ancients and visible to the naked eye Named for: Roman god of agriculture Diameter: 74,900 miles (120,500 km) Orbit: 29.5 Earth years Day: About 10.5 Earth hours Related: Near-infrared views of Uranus reveal its otherwise faint ring system, highlighting the extent to which the planet is tilted. Credit: Lawrence Sromovsky, (Univ. Wisconsin-Madison), Keck Observatory Uranus The seventh planet from the sun, Uranus is an oddball. It’s the only giant planet whose equator is nearly at right angles to its orbit — it basically orbits on its side. Astronomers think the planet collided with some other planet-size object long ago, causing the tilt. The tilt causes extreme seasons that last 20-plus years, and the sun beats down on one pole or the other for 84 Earth-years. Uranus is about the same size as Neptune. Methane in the atmosphere gives Uranus its blue-green tint. It has numerous moons and faint rings.

Discovery: 1781 by William Herschel (was thought previously to be a star) Named for: Personification of heaven in ancient myth Diameter: 31,763 miles (51,120 km) Orbit: 84 Earth years Neptune’s winds travel at more than 1,500 mph, and are the fastest planetary winds in the solar system. Credit: NASA/JPL Neptune The eighth planet from the sun, Neptune is known for strong winds — sometimes faster than the speed of sound. Neptune is far out and cold. The planet is more than 30 times as far from the sun as Earth. It has a rocky core. Neptune was the first planet to be predicted to exist by using math, before it was detected. Irregularities in the orbit of Uranus led French astronomer Alexis Bouvard to suggest some other might be exerting a gravitational tug. German astronomer Johann Galle used calculations to help find Neptune in a telescope. Neptune is about 17 times as massive as Earth. Discovery: 1846 Pluto and its moons orbit the sun near the edge of our solar system.

Learn all about Pluto's weirdly eccentric orbit, four moons and more in this Space.com infographic . Credit: SPACE.com/Karl Tate Pluto (Dwarf Planet) Once the ninth planet from the sun, Pluto is unlike other planets in many respects. It is smaller than Earth's moon. Its orbit carries it inside the orbit of Neptune and then way out beyond that orbit. From 1979 until early 1999, Pluto had actually been the eighth planet from the sun. Then, on Feb. 11, 1999, it crossed Neptune's path and once again became the solar system's most distant planet — until it was demoted to dwarf planet status. Pluto will stay beyond Neptune for 228 years. Pluto’s orbit is tilted to the main plane of the solar system — where the other planets orbit — by 17.1 degrees. It’s a cold, rocky world with only a very ephemeral atmosphere. NASA's New Horizons mission performed history's first flyby of the Pluto system on July 14, 2015.

[Related: New Horizons' Pluto Flyby: Latest News, Images and Video ] Discovery: 1930 by Clyde Tombaugh Named for: Roman god of the underworld, Hades Diameter: 1,430 miles (2,301 km) Orbit: 248 Earth years NASA Solar System Exploration: Dwarf Planets Planet Nine Planet Nine orbits the sun at a distance that is 20 times farther out than the orbit of Neptune. (The orbit of Neptune is 2.7 billion miles from the sun at its closest point.) The strange world's orbit is about 600 times farther from the sun than the Earth's orbit is from the star. Scientists have not actually seen Planet Nine directly . Its existence was inferred by its gravitational effects on other objects in the Kuiper Belt, a region at the fringe of the solar system that is home to icy objects left over from the birth of the sun and planets. What is the Closest Planet to Earth – Mars, Venus, or Mercury? | Outer Space Universe What is the Closest Planet to Earth – Mars, Venus, or Mercury?

March 4th, 2011 | Author: Brian - Staff Writer Planet Earth is the third planet closes to the sun. Using the old saying, “My Very Educated Mother Just Served Us Nine Pizzas,” it can be remembered that the order of the planets goes like this: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto (if you consider it to be a planet). Accordingly, it would seem as though either Venus or Mars would be the closes planet to Earth. But which is it? Asking which planet is the closest to Earth is actually something of a trick question – the closest planet to Earth can change depending on the day, month, or even year. Rather than stating a time frame to describe when a given planet will be closest to our own planet, it is actually most accurate to describe a position that would indicate which planet is closes to ours. Since every planet has its own orbit around the Sun, and every orbit is a different length, all planets have different periods that would signify a year (or a complete orbit of the Sun). When Venus is in the middle of the Sun and Earth, it is at its closest point to Earth.

During this period, Venus would be the closest planet to Earth. However, there are times when Mars is actually the closest planet. For example, during August 2003, Earth and Mars were at such a point in their orbits that Mars was at one of its closest distances to Earth. It was only around 35 million miles away from the planet, which may sound like a long distance but is actually close considering it can be over 200 million miles apart from the Earth depending on where each planet is in its orbit. Given this relatively close distance, Mars was actually closer to Earth than Venus was at this time. On rare occasions, Mercury can be the closest planet. For example, over 2,000 years ago, Mercury was only around 35 million miles away from our own planet. However, occurrences like this are extremely rare and can happen thousands of years apart. Related articles: Mars Close Approaches | Mars Exploration Program Mars Close Approach to Earth: May 30, 2016 See Mars in the Night Sky! Simply go outside and look up, contact your local planetarium, or look for a star party near you.

In 2016, the planet Mars will appear brightest from May 18 to June 3. Mars Close Approach is May 30, 2016. That is the point in Mars' orbit when it comes closest to Earth. Mars will be at a distance of 46.8 million miles (75.3 million kilometers). Mars reaches its highest point around midnight -- about 35 degrees above the southern horizon, or one third of the distance between the horizon and overhead. Mars will be visible for much of the night. By mid-June, Mars will become fainter as Mars and Earth travel farther away from each other in their orbits around the Sun. Miss seeing Mars Close Approach in 2016? The next Mars Close Approach is July 31, 2018. You need a iFrames Capable browser to view this content. What's Up For May 2016 What can you see in the sky this month? Mercury transits the sun and Mars is closer to Earth than it has been in 11 years. Watch to learn how and where to look for them.

In 2016, Mars will appear brightest from May 18-June 3. Its closest approach to Earth is May 30. That is the point in Mars' orbit when it comes closest to Earth. Mars will be at a distance of 46.8 million miles (75.3 million kilometers). Credit: NASA/JPL-Caltech Mars Close Approach What is Mars Close Approach? Close approach is when Mars and Earth come nearest to each other in their orbits around the sun. Close is a relative term. The minimum distance from the Earth to Mars is about 54.6 million kilometers. However, that doesn't happen very often. If Earth and Mars had perfectly circular orbits, their minimum distance would always be the same. However, they have elliptical (egg-shaped) paths. In addition, gravitational tugging by planets constantly changes the shape of their orbits a little bit. Giant Jupiter especially influences the orbit of Mars. The orbits of Mars and Earth are also slightly tilted with respect to each other. All of these factors mean that not all close encounters are equal. In 2003 , Mars made its closest approach to Earth in nearly 60,000 years!

It won't be that close again until the year 2287. When Mars and Earth are close to each other, Mars appears very bright in our sky. It also makes it easier to see with telescopes or the naked eye. The Red Planet comes close enough for exceptional viewing only once or twice every 15 or 17 years. Close Approach: Mars Hoax However, don't be fooled by the Mars Hoax! Since 2003 , this urban legend gets circulated through email and social media every time Mars makes a close approach. The message is that Mars will look as big as the Moon in our night sky. If that were true, we'd be in big trouble given the gravitational pulls on Earth, Mars, and our Moon! When does Mars Close Approach Occur? Mars Close Approach happens about every 26 months. It is closely related to Mars Opposition and Mars Retrograde . Since Mars and Earth are at their closest, it's generally the best time to go to Mars. Many Mars missions have taken advantage of the close distance to visit the red planet.

That's why, depending on budgets, you'll often see that Mars missions launch about every two years: Mars closest to Earth on May 30 | Tonight | EarthSky Mars closest to Earth on May 30 By Bruce McClure in Tonight | May 30, 2016 Image at top from the Hubble Space Telescope on May 12. On May 30, 2016, the red planet Mars comes closer to Earth than it has been since November 2005. It lies 46.8 million miles (75.3 million km) from Earth on this date. This is Mars’ closest point for this year. That’s in spite of the fact that Earth passed between Mars and the sun (the Martian opposition) on May 22. View larger . In 2016, Mars will appear brightest from May 18-June 3. Its closest approach to Earth is May 30. That is the point in Mars’ orbit when it comes closest to Earth. Mars will be at a distance of 46.8 million miles (75.3 million kilometers).

Credit: NASA/JPL-Caltech Why wouldn’t we be closest to Mars on the day we pass between it and the sun? If both the Earth and Mars circled the sun in perfect circles, and on the same exact plane, the distance between Earth and Mars would always be least on the day of Mars’ opposition. But we don’t live in such a perfect universe. Planets have elliptical orbits and a perihelion (closest point) and aphelion (farthest point) from the sun. Mars orbit around the sun takes 687 days in contrast to 365 days for Earth. It has a year nearly twice as long as ours. Earth’s closest point to the sun comes yearly, in January. Mars will be closest to the sun next on October 29, 2016. Right now, with each moment that passes, Mars is still drawing closer to the sun. And that is how its distance from us can be less on May 30 than on May 22, when Earth passed between the sun and Mars. Generally speaking, Mars is brightest in 2016 from about May 18 to June 3.

It is now shining nearly on par with the planet Jupiter, and it’s not very often that Mars can match Jupiter in brilliance! You might think Mars should be brighter when closest to Earth on May 30 than when it was at opposition on May 22. Although Mars is still plenty bright, it’s a tiny bit fainter than at its May 22 opposition. That’s because of something known as opposition surge . Mars DIRECTLY reflects sunlight back to Earth at opposition, accentuating Mars’ brilliance. Before and after opposition, sunlight is reflected at a slightly slanted angle relative to Earth, thereby reducing Mars’ brightness. Tonight’s close encounter between the Earth and Mars will be the closest until around the time of the Martian opposition on July 27, 2018. Artist’s illustration of the orbits of Earth and Mars, via NASA. Artist’s illustration of the relative tilts of the orbits of Earth and Mars, via NASA. Although its exact closest point in 2016 is May 30, in contrast to May 22 for opposition, Mars always comes closest to Earth at the vicinity of opposition.

The time interval between a Mars’ opposition and its least distance from Earth can be as long as 8.5 days (1969), or as little as 10 minutes (2208 and 2232). Earth orbits closer to the sun than Mars does, and we move in orbit more swiftly than Mars. Our world gains a lap on Mars on average about every 780 Earth days, or slightly over every two years. Mars at opposition in 2016, in comparison to 2018, as viewed through a telescope. Illustration via nasa.tumblr.com . The cycle of Mars’ very best appearances in our sky recurs every 15 to 17 years. Mars will have one of those amazing years in 2018, when Mars comes to within 0.38496 astronomical units of Earth on July 31, 2018. (One astronomical unit = Earth/sun distance.) The last amazing year occurred in 2003, when Mars was only 0.37272 astronomical units from Earth on August 27, 2003.

Earth swings between Mars and the sun every other year, although at progressively later dates. Earth will next lap Mars on July 27, 2018. Its closest approach to Earth that year will be July 31. After that, Earth will next lap Mars on October 13, 2020. Mars makes a prominent triangle with 2 other objects – the planet Saturn and star Antares in Scorpius – in 2016. Watch for them in the east each evening, south at your local midnight (or north if you are in the S. Hemisphere) and in the west before dawn. Mars is out almost all night long now. It looks like a bright reddish star, shining with a steadier light than the twinkling stars. Look for Mars in the eastern sky at nightfall – highest in the sky near midnight – and in the west as morning dawn starts to light the sky. What is the Closest Planet to Earth? - Universe Today Universe Today What is the Closest Planet to Earth?

Article Updated: 23 Dec , 2016 by Matt Williams A common question when looking at the Solar System and Earth’s place in the grand scheme of it is “which planet is closest to Earth?” Aside from satisfying a person’s general curiosity, this question is also of great importance when it comes to space exploration. And as humanity contemplates mounting manned missions to neighboring planets, it also becomes one of immense practicality. If, someday, we hope to explore, settle, and colonize other worlds, which would make for the shortest trip? Invariable, the answer is Venus . Often referred to as “ Earth’s Twin “, Venus has many similarities to Earth. It is a terrestrial planet, it orbits within the Sun’s habitable zone, and it has an atmosphere that is believed to have once been like Earth’s. Combined with its proximity to us, its little wonder we consider it our twin.

Venus’ Orbit: Venus orbits the Sun at an average distance (semi-major axis) of 108,208,000 km (0.723 AUs), ranging between 107,477,000 km (0.718 AU) at perihelion and 108,939,000 km (0.728 AU) at aphelion. This makes Venus’ orbit the least eccentric of all the planets in the Solar System. In fact, with an eccentricity of less than 0.01, its orbit is almost circular. Earth and Venus’ orbit compared. Credit: Sky and Telescope When Venus lies between Earth and the Sun, it experiences what is known as an inferior conjunction. It is at this point that it makes its closest approach to Earth (and that of any planet) with an average distance of 41 million km (25,476,219 mi). On average, Venus achieves an inferior conjunction with Earth every 584 days. And because of the decreasing eccentricity of Earth’s orbit, the minimum distances will become greater over the next tens of thousands of years.

So not only is it Earth’s closest neighbor (when it makes its closest approach), but it will continue to get cozier with us as time goes on! Venus vs. Mars: As Earth’s other neighbor, Mars also has a “close” relationship with Earth. Orbiting our Sun at an average distance of 227,939,200 km (1.52 AU), Mars’ highly eccentric orbit (0.0934) takes it from a distance of 206,700,000 km (1.38 AU) at perihelion to 249,200,000 km (1.666 AU) at aphelion. This makes its orbit one of the more eccentric in our Solar System, second only to Mercury For Earth and Mars to be at their closest, both planets needs to be on the same side of the Sun, Mars needs to be at its closest distance from the Sun (perihelion), and Earth needs to be at its farthest (aphelion).

This is known as opposition, a time when Mars appears as one of the brightest objects in the sky (as a red star), rivaling that of Venus or Jupiter. The eccentricity in Mars’ orbit means that it is . Credit: NASA But even at this point, the distance between Mars and Earth ranges considerably. The closest approach to take place occurred back in 2003, when Earth and Mars were only 56 million km (3,4796,787 mi) apart. And this was the closest they’d been in 50,000 years. The next closest approach will take place on July 27th, 20178, when Earth and Mars will be at a distance of 57.6 million km (35.8 mi) from each other. It has also been estimated that the closest theoretical approach would take place at a distance of 54.6 million km (33.9 million mi). However, no such approach has been documented in all of recorded history. One would be forced to wonder then why so much of humanity’s exploration efforts (past, present and future) are aimed at Mars.

But when one considers just how horrible Venus’ environment is in comparison, the answer becomes clear. Exploration Efforts: The study and exploration of Venus has been difficult over the years, owing to the combination of its dense atmosphere and harsh surface environment. Its surface has been imaged only in recent history, thanks to the development of radar imaging. However, many robotic spacecraft and even a few landers have made the journey and discovered much about Earth’s closest neighbor. The first attempts were made by the Soviets in the 1960s through the Venera Program . Whereas the first mission ( Venera-1 ) failed due to loss of contact, the second ( Venera-3 ) became the first man-made object to enter the atmosphere and strike the surface of another planet (on March 1st, 1966). This was followed by the Venera-4 spacecraft, which launched on June 12th, 1967, and reached the planet roughly four months later (on October 18th). The first color pictures taken of the surface of Venus by the Venera-13 space probe. Credit: NASA NASA conducted similar missions under the Mariner program.

The Mariner 2 mission, which launched on December 14th, 1962, became the first successful interplanetary mission and passed within 34,833 km (21,644 mi) of Venus’ surface. Between the late 60s and mid 70s, NASA conducted several more flybys using Mariner probes – such as the Mariner 5 mission on Oct. 19th, 1967 and the Mariner 10 mission on Feb. 5th, 1974. The Soviets launched six more Venera probes between the late 60s and 1975, and four additional missions between the late 70s and early 80s. Venera-5 , Venera-6 , and Venera-7 all entered Venus’ atmosphere and returned critical data to Earth. Venera 11 and Venera 12 detected Venusian electrical storms; and Venera 13 and Venera 14 landed on the planet and took the first color photographs of the surface.

The program came to a close in October 1983, when Venera 15 and Venera 16 were placed in orbit to conduct mapping of the Venusian terrain with synthetic aperture radar. By the late seventies, NASA commenced the Pioneer Venus Project , which consisted of two separate missions. The first was the Pioneer Venus Orbiter , which inserted into an elliptical orbit around Venus (Dec. 4th, 1978) to study its atmosphere and map the surface. The second, the Pioneer Venus Multiprobe , released four probes which entered the atmosphere on Dec. 9th, 1978, returning data on its composition, winds and heat fluxes. Artist’s impression of NASA’s Pioneer Venus Orbiter in orbit around Venus. Credit: NASA In 1985, the Soviets participated in a collaborative venture with several European states to launch the Vega Program . This two-spacecraft initiative was intended to take advantage of the appearance of Halley’s Comet in the inner Solar System, and combine a mission to it with a flyby of Venus.

While en route to Halley on June 11th and 15th, the two Vega spacecraft dropped Venera-style probes into Venus’ atmosphere to map its weather. NASA’s Magellan spacecraft was launched on May 4th, 1989, with a mission to map the surface of Venus with radar. In the course of its four and a half year mission, Magellan provided the most high-resolution images to date of the planet, was able to map 98% of the surface and 95% of its gravity field. In 1994, at the end of its mission, Magellan was sent to its destruction into the atmosphere of Venus to quantify its density. Venus was observed by the Galileo and Cassini spacecraft during flybys on their respective missions to the outer planets, but Magellan was the last dedicated mission to Venus for over a decade. It was not until October of 2006 and June of 2007 that the MESSENGER probe would conduct a flyby of Venus (and collect data) in order to slow its trajectory for an eventual orbital insertion of Mercury.

The Venus Express , a probe designed and built by the European Space Agency, successfully assumed polar orbit around Venus on April 11th, 2006. This probe conducted a detailed study of the Venusian atmosphere and clouds, and discovered an ozone layer and a swirling double-vortex at the south pole before concluding its mission in December of 2014 . Since December 7th, 2015, Japan’s Akatsuki has been in a highly elliptical Venusian orbit. Because of its hostile surface and atmospheric conditions, Venus has proven to be a tough nut to crack, despite its proximity to Earth. In spite of that, NASA, Roscosmos, and India’s ISRO all have plans for sending additional missions to Venus in the coming years to learn more about our twin planet. And as the century progresses, and if certain people get their way, we may even attempt to send human colonists there ! If you’d like more info on Earth, check out NASA’s Solar System Exploration Guide on Earth . And here’s a link to NASA’s Earth Observatory . Astronomy Cast also has an interesting episode on the subject. Listen here, Episode 50: Venus .

Share this: If Venus once had an atmosphere similar to Earth, what happened? I understand the average temperature on Venus now exceeds a uniform 900 degrees Fahrenheit over the entire planet! Helio George Mars Opposition | Mars Exploration Program Read Featured Story | View Image Like all the planets in our solar system, Earth and Mars orbit the sun. But Earth is closer to the sun, and therefore races along its orbit more quickly. Earth makes two trips around the sun in about the same amount of time that Mars takes to make one trip. So sometimes the two planets are on opposite sides of the sun, very far apart, and other times, Earth catches up with its neighbor and passes relatively close to it. What is Opposition? During opposition, Mars and the sun are on directly opposite sides of Earth. From our perspective on our spinning world, Mars rises in the east just as the sun sets in the west. Then, after staying up in the sky the entire night, Mars sets in the west just as the sun rises in the east. Since Mars and the sun appear on opposite sides of the sky, we say that Mars is in "opposition." If Earth and Mars followed perfectly circular orbits, opposition would be as close as the two planets could get.

Of course, nothing about motion in space is quite that simple! Our orbits are actually elliptical (oval-shaped), and we travel a little closer to the sun at one end of our orbits than at the other end. When Can Opposition Occur? An illustration of the relative 'tilt' in the orbits of Earth and Mars Mars oppositions happen about every 26 months. Every 15 or 17 years, opposition occurs within a few weeks of Mars' perihelion (the point in its orbit when it is closest to the sun). This year, Mars opposition occurs on May 22, 2016. An opposition can occur anywhere along Mars' orbit. When it happens while the red planet is closest to the sun (called "perihelic opposition"), Mars is particularly close to Earth. If Earth and Mars both had perfectly stable orbits, then each perihelic opposition would bring the two planets as close as they could be. That's almost the way it is. But once again, nature throws in a few complications. Gravitational tugging by the other planets constantly changes the shape of our orbits a little bit. Giant Jupiter especially influences the orbit of Mars.

Also, the orbits of Earth and Mars don't lie in quite the same plane. The paths the planets take around the sun are slightly tilted with respect to each other. So, with all these added factors, some perihelic oppositions bring us closer together than others. The 2003 opposition was the closest approach in almost 60,000 years! Mars' orbit is more elliptical than Earth's, so the difference between perihelion and aphelion is greater. Over the past centuries, Mars' orbit has been getting more and more elongated, carrying the planet even nearer to the sun at perihelion and even farther away at aphelion. So future perihelic oppositions will bring Earth and Mars even closer. But we'll still have bragging rights for awhile. Our 2003 record will stand until August 28, 2287! Loading the player ... The Opposition of Mars in 2014 A new ScienceCast video previews the April 2014 close approach of Mars.

Read related article: The Opposition of Mars Earth Is Closest to the Sun for 2013 Today Earth Is Closest to the Sun for 2013 Today Geoff Gaherty Pin it Share The orbits of the four inner planets: Mercury, Venus, Earth, and Mars. On Jan. 2, 2013, the Earth is at perihelion, its closest point to the sun of the year. More If the sun looks a little larger than usual today, you're not seeing things. Today (Jan. 2) marks the time when the Earth is at perihelion, the point in its orbit at which it is closest to the sun. During perihelion, the Earth is exactly 91,402,560 miles (147,098,161 kilometers) from the sun.In actuality, you most likely can't see any difference between the apparent size of the sun today and its appearance at aphelion (when the Earth will be farthest from the star).The difference is only 3.4 percent, too small to be detected with the naked eye.

On average, the Earth is about 93 million miles (150 million km) from the sun. It will be farthest from the sun on July 5, when the Earth reaches aphelion, a point 94,508,960 miles (152,097,427 km) from the sun. The closest and farthest differences from the sun are very similar because the Earth’s orbit is very close to being circular. In fact, as planetary orbits go, ours is close to perfect. The eccentric Earth Only Venus and Neptune have more circular orbits than the Earth. On the other hand, if you look at the diagram of the orbits of the four inner planets accompanying this story, you may easily see that Mercury and Mars have orbits which are seriously eccentric. Astronomers use the term "eccentric" in its original mathematical sense, meaning "away from the center." A perfect circle has an eccentricity of 0. A straight line would have an eccentricity of 1. Everything else in between is an oval of some kind.

Here's a look at the innermost planets of the solar system in order of increasing eccentricity: Venus: 0.006785 Mars: 0.093277 Mercury: 0.205649 Looking at the diagram, the orbits of Earth and Venus look almost perfectly circular, while that of Mars is slightly closer to the sun towards the bottom. Mercury's orbit is very much closer to the sun on the right. If you look closely, there is a little tick mark on the orbits to indicate where perihelion lies. Don't confuse this mark with the little wedges which denote the orbital nodes, the points where the orbits cross the plane of the ecliptic. The Earth appears right next to the tick mark on its orbit marking perihelion in the image. Closer to the sun So what is the difference for the inhabitants of Earth when our planet is at perihelion instead of aphelion? The Earth is slightly warmer than it would be otherwise, about 4 degrees Fahrenheit (2.3 degrees Celsius). [ Earth Quiz: How Well Do You Know Our Planet?

] This perihelion effect is very minor compared to the effects of the tilt of our planet's axis. During December in the Northern Hemisphere, the North Pole is tilted away from the sun so that we receive less sunlight every day. At the same time, the South Pole is tilted towards the sun, so the Southern Hemisphere receives more sun and experiences summer. In June, the situation is reversed and we have summer in the northern hemisphere and winter in the southern hemisphere. The only effect of perihelion is that the winters in the Northern Hemisphere are very slightly milder than the winters in the southern hemisphere at the equivalent latitudes. Not as many people live as close to the South Pole as do close to the North Pole, so humanity isn't affected much. So enjoy that "big" January sun, and look forward to the longer days to come as Earth moves around its orbit to the point where we really receive more sun and spring arrives. This article was provided to SPACE.com by Starry Night Education , the leader in space science curriculum solutions. Follow Starry Night on Twitter @StarryNightEdu .

Question: Which planet comes closest to the earth in its orbit around the sun?
Answer: Venus