recursal/Fanatic-Fandom huggingface dataset:
Kepler (Astronomer)

## Kepler (Astronomer)

  **Type**
  **Variety**
  **How Long Ago?**
  **Discussed in**
 Solar System

Johannes Kepler was a German astronomer who was involved in Heliocentric
Model and its development. Using Tycho’s data, he determined that
the orbits of the planets were not circles as previously thought,
but were ellipses. He observed the supernova SN 1604.
NGC 3344

​**Type**
 ​**Variety**
 ​**How Far Away is it?**
 ​**Appears in**

This galaxy is a barred spiral galaxy that is about half the size of the milky way. The swirly spiral arms are the birthplace of new stars- their high temperature makes them shine blue. Clouds of dust and gas that appear red are resovoirs for new stellar material.
NGC 4603

## NGC 4603

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Local Superclusters

It is the most distant galaxy in which Cepheid variables have
been found. Clusters of young bright blue stars highlight the galaxy's spiral
arms. In contrast, red giant stars in the process of dying are also found. Only
the very brightest stars in NGC 4603 can be seen individually. Much of the
diffuse glow comes from fainter stars that cannot be individually
distinguished.
NGC 4522

## NGC 4522

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Virgo Supercluster

NGC 4522 is an example of a spiral galaxy in which a
strong wind is being sent out across the galaxy from the center, causing star
formation regions ­to collapse and form stars. The wind is also
stripping the galaxy of its gas content, however, so star formation will cease
to exist soon.
LRLL 54361 (In IC 348)

## LRLL 54361 in IC 348

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 2013

This mysterious infant star, swaddled inside a dusty blanket,
behaves like a police strobe light. The newly discovered object offers clues
into the early stages of star formation, when a lot of gas and dust is being
rapidly sucked into a newly forming binary star.
GRO J1655-40

## GRO J1655-40 Binary

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Milky Way

This X-ray binary star system consisting of an evolving
primary star and a massive but unseen companion. They orbit each other every
2.6 days. X-ray emissions most likely come from the accretion disk that
surrounds the black hole.
Magnetar

## Magnetar

A magnetar is a spinning neutron star with an intense
magnetic field. Magnetic field strength is measured in units called gauss. A
refrigerator magnet is around 50 gauss. MRI’s use up to 70,000 gauss. A
magnetar’s field strength is a thousand trillion gauss – enough to tear atoms
apart a 1000 km away. Only around one in ten neutron stars start out as a
magnetars. We do not yet know what makes their magnetic fields so strong. But
it looks like they don’t last long. They settle into normal neutron star status
after around 10,000 years.

One of the most fascinating aspects of magnetars is how they
can have starquakes - earthquakes, but on stars. When neutron stars form, they
can have a crust on the outside, surrounding the matter inside. This crust of
neutrons can crack, like the tectonic plates on Earth. As this happens, the
magnetar releases a blast of radiation like the solar flare we saw earlier, but
millions of times stronger
Castor

## Castor

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Nearby Stars

Castor is a complex system of stars that consists of
one of the largest stable star systems discovered with three components.
It may not sound like much until you realize each component is a binary
system for a total of 6 stars in the system!
Necklace Nebula

## Necklace Nebula

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Planetary Nebula

Necklace nebula is a planetary nebula that lies very far
away. It has a bright ring measuring 19 trillion kilometers (2 light years)
across. The bright knots of gas resemble the diamonds that one can find within
a necklace.
Earth (episode)

## Earth Distances (Episode)

  **Type**
  **Series**
  **How Many minutes is It**
  **Covers**
 Earth, Cosmic Distance Ladder

Earth is the second episode of the first video book, How Far Away is it? In
this episode, David starts in his backyard and introduces the Cosmic
Distance Ladder. He uses direct measurement to find the distance to
a pole, and introduces Triangulation as a method of indirectly
finding distance. After using it to find the distance to a rock in his
backyard, he covers the different subdivisions of a degree and angle
measurement, then goes on to cover how triangulation was used to measure the
height of Mt. Everest and the width of the Grand Canyon. He then
covers the limitations of triangulation, and how we can overcome these
limits. Two ways we can is to know something about the object, as he
introduces with lightning, and to actually go there, which he
demonstrates by describing the Earth’s atmosphere. Then, he covers how
to find the Earth’s radius using geometry and describes Eratosthenes’
approach, which was only 1% off. He then shows pictures of cities taken
from the ISS and measures distances to them from San Diego.
Lastly, he shows an overview of the cosmic distance ladder.

It was updated to 4K on October 22, 2016

## **Objects Covered and Timestamps**

Earth (planet) 0:00, 8:08

Direct Measurement 0:45, 7:57

Triangulation 1:12, 3:50

Angles 2:30

Grand Canyon 3:15

Mt Everest 3:36

Lightning 4:30

Atmosphere 5:38, 6:48

Balloons 6:15

Eratosthenes 8:13

Distance-Dependent Measurements 10:20

Cities 11:32

Cosmic Distance Ladder 14:30

Parallax 15:12

Standard Candles 16:05

Redshift 16:50

## **Classroom Aids**

Classroom aids were released for this section on October 19, 2016. Here they are with their time stamp information as they correlate with the main video:

Triangulating the Earth (0:00 to 3:49)

Distance to Lightning (3:50 to 5:37)

How High is the Sky (5:38 to 8:07)

How Big is the Earth (8:08 to 11:31)

Distance to Cities (11:32 to 14:29)

Cosmic Distance Ladder Introduction (14:30 to 17:44)

How Far Away is it Preview (17:45 to end of video at 19:02)
Gamma Cassiopeia

​**Type**
 ​**Variety**
 ​**How Far Away is it?**
 ​**Appears in**

It is a blue white subgiant variable star with a mass 19 times that of the sun, and a brightness 65000 times greater than the sun. IC 63, called the Ghost of Cassiopeia, lies close to the star and is a reflection nebula (and emission nebula) illuminated from the powerful radiation of the star.

Ghost:
NGC 6791

## NGC 6791

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Star Clusters + Supernova

NGC 6791 is an open cluster that is actually one of the
largest and oldest open clusters known in our galaxy. It is 10 times larger
than most open clusters and contains roughly 10,000 stars in total. It is
roughly 8 billion years old and has stayed together for so long due to its
mass.
NGC 1309

## NGC 1309

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Virgo Supercluster

NGC 1309 is one of the 200 galaxies that make up the Eridanus
Galactic Group. It was home to the Type Ia supernova SN 2002FK and
hosts a number of Cepheid variable stars as well resolved by Hubble
Space Telescope. The type Ia was shown to be an excellent standard
candle.
Interacting Galaxies (Object)

## Interacting Galaxies

An interacting galaxy, also known as an interacting galaxy
pair or colliding galaxies, are an event that occurs when two galaxies begin to
gravitationally affect one another. Our nearest star, Proxima Centauri, is 4
light years away. Those large distances between stars mean that it’s a million
to one shot that any star will actually collide when the galaxies pass through
each other. But the form and shape will change dramatically and change forever
for the interacting galaxies themselves. The key factors are the shapes and
relative masses of the colliding galaxies, the collision velocity, and the
angle of collision, a glancing blow vs. a head on collision, they’ll have
different outcomes. For example, a smaller galaxy colliding with a big one will
only distort the larger one while two large galaxies interacting could result
in their merger into an elliptical.
Kiso 5639

## Kiso 5639

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 2016

A firestorm of star birth is lighting up one end of this
dwarf galaxy Kiso 5639. The galaxy is shaped like a flattened pancake, but
because it is tilted edge-on to our view, it resembles a skyrocket, with a
brilliant blazing head and a long, star-studded tail. Kiso 5639 is a rare,
nearby example of elongated galaxies that occur in abundance at larger
distances, where we observe the universe during its earlier epochs.
Markarian 266

## Markarian 266/NGC 5256

 ​**Type**
 ​**Variety**
 ​**How Far Away is it?**
 ​**Appears in**

Its odd shape is due to the fact it is not one galaxy. The two disk galaxies are just 13,000 light years apart. Their gas is swirling around to make thousands of new stars across the galaxy. In addtion, each galaxy has an active galactic nucleus with gas feeding Supermassive black holes.
Milky Way Galaxy

**Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Milky Way

The Milky Way Galaxy is our galaxy that the sun is currently
located within. It is a collection of gas, dust, dark matter, and hundreds of
billions of stars. Our galaxy appears to be a barred spiral. However, a full
image of the galaxy is not available because we are located inside of it, so we
have to view it all around us. In addition, the massive amounts of dark clouds
surrounding the center of the galaxy prevents us from seeing to the other side.

**History**

After it was discovered that all the stars burn with their
own light, a cosmology was constructed in which all the stars were in the Milky
Way Galaxy. In the early 20th century, Edwin Hubble changed this
viewpoint by discovering that the Andromeda Nebula was actually another galaxy.
Later on, Shapley mapped globular clusters to find out that the sun was not the
center of the Milky Way. And recently in the 21st century, we
discovered that our solar system orbits the galaxy’s supermassive black hole. In
4 billion years, it will collide with Andromeda.

**Structure**

The Milky Way galaxy is a barred spiral galaxy consisting of
multiple spiral arms and hundreds of billions of stars. It is composed of a few
different components: a disk, a central bulge, a halo, and a galactic center.

Remember that if you see an image of the whole Milky Way, it
is only an artist’s conception since we can’t see the whole galaxy. The galaxy
is so big that the distance one must go to see it all is 32,000 light years. If
Voyager 1 was aimed at this photographic point, it wouldn’t reach it for
another 558 million years. From this view, the area that marks our stellar
neighborhood would be little more than a pixel.

The Milky Way is orbited by at least 16 dwarf galaxies,
including the SMC and the LMC, and a lot of other galaxies. They all require
billions of years to orbit. Sagittarius Dwarf is the closest and is being
ripped apart by our own galaxy.

The galaxy's central region is a dynamic hub of stars of various ages and compositions zipping around at different speeds. This supports the theory that the bulge formed later than the rest of the galaxy.
Great Attractor

## Great Attractor

Normally, galaxies are expected to have a motion consistent with
the Hubble flow. That is, given the Hubble law, and the distance to a galaxy,
its velocity is set. But in our local area, within 1 billion light years, there
is an additional flow superimposed on the Hubble flow. It appears that our
galaxy and a large number of the galaxy superclusters in our area are flowing
towards what is called the great attractor.

Initially, it looked like the great attractor was located
close to the Norma Cluster, not too far from the Centaurus Supercluster. But
Norma is so close to our galactic plane or area of avoidance that we cannot see
into it very well. More recently, updates to motion vectors indicate that the
flow is not so much to the Norma Cluster, but to the much more massive Shapley
Supercluster behind it.
Dark Matter (Substance)

## Dark Matter (Particle)

Dark matter is an (as of yet) hypothetical particle that is
responsible for motions of galaxies that shouldn’t be as large under Newton and
Einstein’s equations. It does not interact with any other particle except with
the force of gravity, so thus it is invisible. It exists in large amounts in
the galaxy’s halo, where it speeds up the rotation of the galactic disk at its
edge.

In the early 1930s Fritz Zwicky, a Swiss astronomer out of
Caltech, studied the Coma galaxy cluster 321 mly away with a thousand galaxies
spanning 25 mly in diameter. He looked at it in a number of ways, two of which
are very revealing. In one he used galaxy motion to calculate mass and in the
other he used galaxy luminosity. Although his calculations were not accurate,
they revealed another force was in play in the cluster that ordinary matter
content could not explain. The luminous matter and total matter were not equal.
This was the first proof of dark matter. Galaxy rotation curves were later used
as well.

Candidates for dark matter: Hydrogen, neutrinos, and WIMPS
Light

## Light/ Color

Light is an electromagnetic radiation created by
moving electrons that travels at a constant speed known as the speed
of light. Although light carries energy, it does not carry mass.
The intensity of light obeys the inverse square rule as well. Light, as
we currently understand it, follows the wave-particle duality described
by quantum mechanics. You can view it as a wave, or as a particle
known as a photon. In order to understand color, the wave nature of
light is examined. It turns out that the wavelength of light is inversely
proportional to the energy of light so that when the wavelength decreases,
energy increases. Frequency is cycles per second of light, and is inversely
proportional to wavelength but directly proportional to energy. Red is low energy
light, along with infrared, microwave, and radio. Violet is high energy light
along with Ultraviolet, X-ray, and gamma ray. This is the electromagnetic
spectrum.
NGC 1052

## NGC 1052-DF2

 ​**Type**
 ​**Variety**
 ​**How Far Away is it?**
 ​**Appears in**

The galaxy is larger than the milky way, but it contains only 1/200 the number of stars. Due to its low density of stars it is classified as an ultra-diffuse galaxy. An interesting thing about this galaxy that could explain its nature is that there is no dark matter binding it together, a very unusual phenomenon.
GJ 1214

## GJ 1214

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Nearby Stars

GJ1214 is a dim red star that is also known as Gliese
1214. In 2009, Hubble observations indicate that GJ 1214 has an orbiting
exoplanet that could potentially be a water world planet. These planets
could potentially hold life! Its name is GJ1214 B.
2013 Update

## Gaia (2013 Update)

  **Type**
  **Series**
  **How Many minutes is It**
  **Covers**
 Variety

Gaia is the eighteenth episode of the first Videobook, How Far Away is it? It
is the first update for the series as well. The update is basically a
mini-version of the entire previous series. He begins with an introduction,
like the Preface
in the series. He begins with the Heliosphere and Voyager’s progress.
He then moves out into the Neighborhood with Proxima Centauri and
explains it more with a better image by Hubble. He then moves out to the Hyades
Cluster and a debris disk. He then covers the Methuselah Star where
it appeared to be older than the universe. In distant stars, he moves out and
talks about light echoes. He then goes into another Cepheid with
light echoes as well. He moves on to planetary nebula and star clusters
like M15. After this, he moves on to star birth nebulae with a sneezing
star. He moves on to the Milky Way with the Halo discovery.
He moves on to the Local Group with the Magellanic Cloud, and
goes on to The Local Volume with M106. He skips the Virgo and
moves on to Local Superclusters with NGC 6984. After this is colliding
galaxies with 2 galaxies. Then the cosmos with a few different
objects. Lastly, he talks about Gaia extensively and goes into the
credits.
NGC 5307

## NGC 5307

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Planetary Nebula

NGC 5307 is a planetary nebula that displays an interesting
spiral pattern which was most likely caused by the central star wobbling as it
expelled jets of gas and dust in different directions. This wobble would most
likely be a result of a binary system.
Altair

## Altair

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Nearby Stars

Altair is a nearby white star to our sun. An
interesting fact about this star is that it is not spherical, like our
sun, but flattened at the poles. This is due to a high rate of rotation causing
a force to compress the equator, causing the star to bulge out at the poles.
Messier 15

## M15

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 2013

It is one of the oldest globular clusters known, with an age
of around 12 billion years. Both very hot blue stars and cooler golden stars
can be seen swarming together in the image, becoming more concentrated towards
the cluster's bright center. As well as stars, M15 was the first cluster known
to host a planetary nebula, and it has been found to have a rare type of
intermediate-mass black hole at its center.
Local Interstellar Neighborhood

## Local Interstellar Neighborhood

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Nearby Stars

The Local interstellar neighborhood is the grouping of nearby
stars that can be easily observed and have parallax measured to.
It is around 25 light years in radius starting with our solar system.
There are 50 noticeable stars, but hundreds of stars in total since most are
hard to see red dwarves. Red dwarves are so hard to see, even the
closest one isn’t visible to naked eye!
Methuselah Star

## Methuselah Star (HD 140283)

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 2013

Currently, based the Hubble Constant, we have the age of the
universe at 13.8 billion years. But here is a nearby star that at first glance
looks like it is 16 billion years old! That would make it older than the
universe! Hubble astronomers are coming to grips with this paradox by improving
the precision of the observations used to estimate the age of this
"Methuselah star." Hubble has helped refine the calculation to 14.5
billion years.
Bubble Nebula

## Bubble Nebula

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 2016

It’s a balloon-like bubble, 7 light-years across, being blown
into space by a super-hot, massive star. The high energy light is from the star
BD +60 2522, an extremely bright, massive, and short-lived star that has lost
most of its outer hydrogen and is now fusing helium into heavier elements. The
star is about four million years old, and in 10 to 20 million years, it will
likely detonate as a supernova. It is responsible for ionizing the entire
region.
Galactic Disk/ Spiral Arms

## Galactic Disk/ Spiral Arms

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Milky Way

The Galactic disk is the region of the galaxy that contains
most of the nebulae and younger stars in the galaxy, with the central bulge
containing older and redder stars. It has a number of spiral arms, which are
known as density waves. They include the two 3 kpc arms, known for their
length; Scutum-Centaurus and Perseus as the main arms; Sagittarius, Norma, and
the Outer Arm as other arms; and a spur off the Sagittarius arm called Orion
Spur. It contains our solar neighborhood, and it is 10,000 light years across.
Star density is same in arms and in gaps.
NGC 6751

## NGC 6751

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Planetary Nebula

NGC 6751 is a planetary nebula is strikingly unusual for
planetary nebulae, and it looks like a giant eye. The nebula is a cloud of dust
and gas ejected a few thousand years ago by the hot star, visible at the center
of the nebula.
Distant Stars (episode)

**Type**
  **Series**
  **How Many minutes is It**
  **Covers**
 Stars, light

Distant Stars is the sixth episode of the first Videobook, How Far Away is it? It
covers the stars that are so far away that even space telescopes can’t
detect an accurate parallax. He uses Betelgeuse as an example and
refers back to it during the episode and introduces the concept of a color-luminosity
diagram that will be built later in the episode. He, again, dives into quantum
mechanics and explains the wave-particle duality and how this is
useful in studying light. He covers the electromagnetic spectrum and the
blackbody radiation. Given this information, he then constructs the
basic HR diagram. He then covers nuclear fusion and how this important
process powers stars at their cores. Using everything covered before, he
discusses the life cycle of most stars and the relationship mass
has with other stellar properties. He then goes into spectral lines and spectral
classification and how we can use the different elements of this
classification to place and plot stars on the HR diagram, thus giving the
luminosity and distance. He then goes back to stargazing and covers Cepheid stars,
in which the period was related to the luminosity giving the first type of standard
candle. He then goes over other stars including hypervelocity stars
and another standard candle, RR Lyrae stars.
Delta Cephei

**Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Distant Stars

Delta Cephei is, like Polaris, a Cepheid variable
star, which is a key rung on our cosmic distance ladder. Its
proximity to us has helped scientists measure its distance through other methods
so that the correlation between luminosity and period could be
configured. It is also binary.
Alpha Centauri System

## Alpha Centauri System

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Nearby Stars

Alpha Centauri A and Alpha Centauri B form a binary system
that represents the closest system to the solar system. If Proxima
Centauri is considered a member of this system, then this system includes
the closest star to our own star. The stars are separated by a distance
equal to that between the Sun and Uranus. Star A is bright and
larger than the sun slightly, while Star B is smaller than the sun and has an
orange tinge. Proxima is a red dwarf star.
Angular Size

## Angular Size

Angular size is a necessary component of measuring distances
to objects on the cosmic distance ladder, and is also essential for
measuring characteristics about an object such as diameter when distance
is known. Angular size is measured in degrees. A circle has 360 degrees. For
greater accuracy, we divide up a degree into 60 arcminutes and each arcminute
into 60 arcseconds. This gives us 3,600 arcseconds in every single degree.
Although a protractor works okay in a backyard setting, it is a crude
instrument that can only measure angles down to a degree. Industrial
instruments like the Theodolite measure angles down to a second of arc. In
space, angular size can grow very small. The moon and sun are a
half of a degree, while most deep space objects can be measured in arcminutes.
It takes a very powerful telescope to detect stellar parallax,
which are less than one arcsecond.
NGC 1300

## NGC 1300

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Virgo Supercluster

NGC 1300 has two main long spiral arms and is a
classic example of a barred spiral galaxy. The single bar at the
center leads into the arms, which wrap around either side of the galaxy. In
this galaxy you can easily see the contrast between yellow bulge and
blue disk.
NGC 3370

## NGC 3370

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Virgo Supercluster

NGC 3370, in 1994, hosted a type Ia Supernova called SN
1994AE that briefly outshone this galaxy’s billions of stars. This supernova
was special because it was one of the nearest and best observed supernovae
since the advent of modern telescopes.

Fun fact: this galaxy is briefly seen in 5:02 in the Solar System video.
Abell 2029

## Abell 2029

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Cosmos

Abell 2029 is an extremely massive galaxy cluster
located only a little bit beyond our local superclusters. It is
dominated by the galaxy IC 1101
which contains most of the cluster’s space and mass. IC 1101 is also the
largest galaxy in the universe so far.
MACS J0025-4-1222

## MACS J0025-4-1222

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Cosmos

This massive cluster is actually a collision of two
clusters that are impacting each other at millions of km/h. It gives
insight into the properties of dark matter (shown in blue). The
collision separated the dark matter from ordinary matter since the
ordinary matter (pink) interacted and clumped in the center while the dark
matter passed right through.
G2 Gas Cloud

**Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Milky Way and 2014

The gas cloud, names G2, was first seen in 2002. Observations
of its trajectory indicate and confirm that it will be brought very close to
Sagittarius A\*. It will make its closest approach to the black hole in 2013. It
was thought that it would get sucked into the black hole, causing an accretion
disk to form, but this did not occur. The theory is that G2 was a binary star
that merged and expelled a lot of gas and dust, giving the illusion of it being
a gas cloud.
Jupiter

**Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Solar System

Jupiter is the largest planet
in the solar system and is also a gas giant planet. Its orbit is fifth
from the sun. It can be thought of as a giant solar system vacuum
cleaner, eating up the sun’s early debris to become larger than any other
planet. It is known for the Great Red Spot.

In 1994, the comet Shoemaker
Levy began to collide with Jupiter, showing the immense size of the planet. The
comet, already broken up by Jupiter’s gravity, began to collide on July 16. The
plumes reached thousands of kilometers high, and to compare, our atmosphere
only extends a few hundred kilometers above us. Over a period of 6 days, 21
distinct impacts were recorded by Galileo spacecraft, and the largest left a
mark the whole Earth could fit into.

It has at least 69 moons but the four largest moons (which Galileo discovered) are Ganymede, Callisto, Io, and Europa.

The Jupiter-sun system sets up a
phenomena called Lagrange points, where small objects can orbit. In
Jupiter’s L4 they are known as Trojans, and for L5 they are Greeks.

NASA's Juno spacecraft arrived at
Jupiter on July 4 after a five-year journey. On Aug 27, it successfully
completed the first, and closest of 36 planned orbital flybys. The spacecraft
flu over the tops of Jupiter's clouds at a distance of just 4,200 kilometers
(2,600 miles). This photograph is the first flyby data to be released. It was
taken from a distance of 703,000 kilometers (437,000 miles).

On April 7 2017 Jupiter was in opposition with Earth, fully illuminated by the sun.
NGC 1277

​**Type**
 ​**Variety**
 ​**How Far Away is it?**
 ​**Appears in**

In the Perseus Cluster, it is thought the galaxy has remained unchanged for the past 10 billion years. NGC 1277 is almost entirely lacking in blue globular clusters so it has experienced very little collisions and star formation over the past billions of years. It is theorized this is due to its speed through the cluster.
J102915

## J102915

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Distant Stars

This star is very faint, and is made up of almost
purely hydrogen and helium, making it a “metal poor star”. Metal poor stars are
one of the oldest stars in the universe, originating the generation after
the very first stars.
Coma Cluster

**Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Local Superclusters

The Coma cluster has received a huge amount of scientific
research. This is partly because it lays a long way from the plane of our
Galaxy and it is largely unobscured by any gas, dust or foreground stars. There
is also one obvious foreground star in this image. It’s less than one millionth
of the distance to the Coma cluster.

Hubble did a study of the coma cluster and found 22,000 globular clusters inside. Some of them were in intergalactic space, ripped from their home galaxies by the cluster's gravitational interactions.
ARP 148

## ARP 148 (Mayall’s Object)

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Interacting Galaxies

Here we see the staggering aftermath of an encounter between
two galaxies, resulting in a ring-shaped galaxy and a long-tailed companion.
The collision between the two parent galaxies produced a shockwave effect that
first drew the matter into the center and then caused it to propagate back outwards
in a ring. The elongated companion perpendicular to the ring suggests that Arp
148 is a unique snapshot of an ongoing collision.
Cosmic Distance Ladder

## Cosmic Distance Ladder

The Cosmic Distance
ladder is the main topic covered by the How Far Away is it video book.
In this video book, David takes a slice of physics and astronomy
and just talks about distance, and how we know how far away things are.
Astronomers use a set of techniques known as a cosmic distance ladder to find
out how far away things are. Each rung on this ladder relies on the rungs
before it. For example, in order to triangulate, one must use direct
measurement to find the baseline. Each step also works for a particular
distance range, and will not work beyond this range. The cosmic distance ladder
is developed throughout the video book. Although advanced astronomers use many
other techniques on their distance ladders, the video book covers the most
important steps.

Here is a list of the
steps-

Earth: Triangulation and
Direct Measurement

Solar System: Direct
Measurement and Parallax

Nearby Stars: Parallax

Distant Stars:
Spectroscopic Parallax, Expansion Parallax, Standard Candles

Nearby Galaxies: RR
Lyrae, Cepheids, Globular Clusters, Nebulae, Type Ia Supernovae

Distant Galaxies:
Cepheids, Globular Clusters, Nebulae, Type Ia Supernovae, Redshift

Most Distant Galaxies:
Redshift
NGC 4302 and NGC 4298

## NGC 4302/NGC 4298

 ​**Type**
 ​**Variety**
 ​**How Far Away is it?**
 ​**Appears in**

Blue in these galaxies indicate large regions of star formation, while brown indicated large amounts of interstellar dust. The galaxy centers are 35,000 light years apart. At the closest point they are only 7000 light years apart. Astronomers wonder why there is no sign of interaction via gravity despite this close arrangement.
N30B

## N30B

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Andromeda

The Double Bubble in N30 B or N 30B is a unique peanut shape
nebula in the large Magellanic cloud. It is an emission nebula that surrounds a
cluster of young hot stars. It is part of another larger nebula as well. Henize
S22, a star, is the one lighting up this larger nebula.
ARP 269

## ARP 269/NGC 4485/NGC 4490

 ​**Type**
 ​**Variety**
 ​**How Far Away is it?**
 ​**Appears in**

24,000 light years currently separates the two galaxies. The two galaxies have already gone through each other and are speeding apart again, but soon they will return due to gravity within a few billion years. 4490 used to be a barred spiral but is now irregular and called the Cocoon Galaxy.
NGC 4319

**Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Virgo Supercluster

NGC 4319 has unusually dark and misshapen dust lanes that
can mean only one thing: sometime in this galaxy’s past, an interaction with
another galaxy must have occurred. These features are prominent in the inner
region of the galaxy shown in the image. It makes a brief appearance in The Cosmos as Quasar
Markarian is located next to it in the sky.
Monkey Head Nebula

## Monkey Head Nebula (NGC 2174)

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 2014

This colorful H II region is filled with young stars embedded
within bright wisps of cosmic gas and dust. The icing on this cosmic birthday
cake takes the form of young white and pink stars sprinkled amongst the glowing
clouds, pushing away the dark stellar nurseries in which they formed.
Laniakea Supercluster

## Laniakea Supercluster

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 2015

Recently, astronomers have redefined superclusters by the
motions of galaxies, which are determined by their redshift and blueshift.
Under this new definition, the Virgo Supercluster is now an arm of a larger
supercluster, known as Laniakea for “Immeasurable heaven”. Perseus-Pisces is
now our adjacent supercluster.
Magnetosphere

**Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Heliosphere

The magnetosphere is the Earth’s magnetic field pushed
back by the solar
wind. Due to this, it appears to be squashed in a very similar way
to the heliosphere. It is very important for life on Earth since it routes charged
particles around the Earth instead of letting them bombard us.
A0620-00

## A0620-00

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Milky Way

A0620-00 is the closest black hole candidate to the Earth and
is a stellar mass black hole. It is a low mass x-ray binary star containing a
small, massive, dark compact object between 3-5 times the mass of the sun. It
has a diameter of 25 miles.
Centaurus Cluster

## Centaurus Cluster

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Local Superclusters

It is one of the most massive assemblages of galaxies in the
nearby universe. Note that the plane of our galaxy cuts its way through this
region of sky, so any photographs will be contaminated by a large number of
foreground Milky Way stars. It is the most massive in the Centaurus
Supercluster.
NGC 4650A

## NGC 4650A

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Local Superclusters

Located about 130 million light-years away in the Centaurus
cluster, NGC 4650A is one of only 100 known polar-ring galaxies. Their unusual
disk-ring structure is not yet well understood. One possibility is that polar
rings are the remnants of colossal collisions between two galaxies sometime in
the distant past, probably at least a billion years ago.
Supernovae (object)

## Supernovae

A supernovae is a class of exploding star and is the
explosion at the end of the life of stars more than 8 times the mass of the sun.
A supernovae can occur when the supergiant star no longer has enough
outward pressure to hold off gravitational collapse. The inward force of
gravity causes the star to collapse inwards until neutron degeneracy pressure
or a black hole formation causes the imploding star to explode. This causes
much of the star’s remaining elements to fuse, releasing an enormous amount of
energy that can outshine a whole galaxy of stars and be visible from 8 billion
light years away. This creates the supernova remnant, which usually contains a
neutron star or black hole at the center. The explosion is billions of times
larger than the novae explosion that form planetary nebulae and release so much
energy that if one were at the distance to Capella from Earth, it would destroy
all life on the planet. In the explosion, the energy releases is equal to the
energy in the entire 10 billion lifetime of our sun. However, for most
explosions across the cosmos, we cannot know their luminosity since that
depends on the mass of the progenitor star. However, a distinct type of supernova
called type Ia always have a similar luminosity, making them important standard
candles.
NGC 3982

## NGC 3982

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Virgo Supercluster

NGC 3982 is a spiral galaxy and proves the point that,
like snowflakes, no two spiral galaxies look exactly the same. It has a large
amount of star birth regions and has long winding spiral arms. It
also has lots of dust lanes that provide the material for the future
generations of stars.
NGC 6946

## NGC 6946/ Fireworks Galaxy

 ​**Type**
 ​**Variety**
 ​**How Far Away is it?**
 ​**Appears in**

```
​ 2017

```

Also known as the fireworks galaxy. N6946-BH1 was found in the galaxy at 25 times mass of sun. The star looked to go supernova, but then its brightness decreased and it dissapeared, so it was assumed it directly collapsed into a black hole instead.
Dwingeloo 1

## Dwingeloo 1

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Local Volume

This newly discovered collection of more than 100 billion
stars has gone undetected previously because it is hidden from view behind our
Milky Way galaxy. The galaxy appears as a distinctive barred-spiral-shaped
object embedded in a dense starfield of hundreds of foreground stars comprising
our own Milky Way galaxy. Because the galaxy is only faintly visible through
obscuring dust and gas in the Milky Way, it is possible that astronomers are
seeing only the central part of a much larger galaxy.
Black Hole

## Black Hole/ Stellar Mass Black Hole

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Milky Way and later

A black hole is an object that is so dense, that not even
light can escape it. There are two main types, stellar mass and supermassive
black holes. Supermassive black holes are thought to form from mergers from the
stellar mass black holes. Black holes are a common concept in general relativity
and gravitational waves, so they are covered in the How fast is it Video Book
as well.
NGC 6822

## NGC 6822

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Andromeda

NGC 6822 is a small irregular galaxy that is one of the MW’s
closest neighbors. It is considered prototypical of the first galaxies that
inhabited the very first part of universe. It has a high abundance of HII
emission nebulae. Hubble V has a diameter of about 200 light years. A faint
tail of nebulosity sits opposite the dense cluster of bright stars in the
irregular nebula.
V838 Monocerotis

**Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Distant Stars

A recent Hubble analysis of this star shows that there
is a dramatic change in the illumination of surrounding dust clouds of this
star. These are known as light echoes. In early 2002, the star suddenly brightened
and began revealing these dust patterns. The star became 600,000 solar
luminosities in a very short time.
Howfarawayisit.com

## Howfarawayisit.com

  **Type**
  **Variety**
  **What is it**
  **Created by**
 David Butler

Howfarawayisit.com is a web resource created by David Butler.
It was designed to accompany the video books but now includes full text
documents and worksheets. In some of the tabs, he describes each segment in
some detail and has the videos there as well. He posts classroom aids as well
to help teachers and educators if they want a good resource in Astronomy,
Quantum Mechanics, and Relativity. He also includes a concept index
with many different terms covered in the series. He then includes documents
with the text of each video, so you can read instead of watch. He also includes
lesson plans with questions and a place where you can contact him.
Gamma Ray Burst

A GRB or gamma ray burst is the largest stellar explosion, and will emit more energy in 10 seconds than the sun in its entire ten billion year lifespan. A gamma ray is an electromagnetic wave with the shortest wavelength. Even as the move across the cosmos the beams of the grb, unlike a supernova, remain intense. There are two beams made in a GRB that are aligned to the poles of the collapsing star. Only very massive stars end their life in GRB and hypernova explosions.

There are two types, short and long. A short will only last for a very short timespan while long can go from thirty seconds to a couple of minutes.
Bow Shock

## Bow Shock

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Heliosphere

The bow shock is like the area in front of a ship where it is
in direct contact with the ocean water. The ship represents the sun
while the ocean water represents the galactic wind. It defines the outer limits
of the heliosphere.
Mars

**Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Solar System

Mars is the furthest planet
from the sun where a person can actually find dry land to stand on.
There are three rovers on Mars, which are digging into the soil, looking for
water, and past signs of life. On midday, temperature is just about freezing,
and during night, it plummets to -73 Celsius (-100 Fahrenheit). Due to orbit
dynamics, the distance between Earth and Mars varies from 55 million kilometers
to 400 million kilometers. Rather than give this distance, it is helpful to
give an average distance to the sun at 230 million kilometers.

Mars is our second closest neighbor next to venus. Iron oxide in the dirt and rocks gives it the characteristic red color. It's tilted like the earth, giving it seasons. Olympus mons, its highest mountain, is three times higher than mount everest, and Valles Marineris is three times longer than the grand canyon! Mars also has two small moons, Phobos and Deimos, which have similar composition to asteroids (so astronomers assume that they are likely captured asteroids)

Back in 2003, the two planets Mars
and Earth reached a near minimum distance of 56 million kilometers
during Opposition. This is when Mars and Earth are on same side as the sun and
their orbits are very close together. The last time they were that close was
50,000 years ago.

In 2016,
Mars reached Opposition again at a distance of 80.5 million kilometers, which
is still not as close as it was in 2003. However it allowed Hubble to see great
detail on Mars. The next opposition was on July 27, 2018 at a distance of 57,775,000 km.
Messier 74

## M74

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Local Volume

This galaxy’s perfectly symmetrical spiral arms emanate from
the central nucleus and are dotted with clusters of young blue stars and
glowing pink HII regions of ionized hydrogen Tracing along the spiral arms are
winding dust lanes that also begin very near the galaxy's nucleus and follow
along the length of the spiral arms.
Main Sequence Stars

## Main Sequence Stars

Main sequence stars are the stars in the universe that
are in the main part of their lifetime, the part where they convert hydrogen to
helium through nuclear fusion. Most stars are currently in the main
sequence phase, including our own sun. The main sequence allows for all
the different colors and luminosities of stars and, on the HR
diagram, they fall on a diagonal line. The hot blue stars at the top
left are very massive, the yellow medium mass stars are similar to the
sun, while the dim, red stars at the bottom right are much less massive
than the sun. When a star runs out of hydrogen fuel, it becomes more reddish
and moves off the main sequence to giants or supergiants.
Inverse Square Rule

**Type**
  **Based On**
  **Covers**
 Gravity, light

The Inverse Square rule, also known as the inverse square
law, is an important tool for understanding how to use Spectroscopic
parallax or standard candles to find distance. Without it, we would
not be able to use standard candles to determine distance. It works for light
and also for gravity in the law of Universal Gravitation. A good way to
view luminosity and gravity is by a field surrounding the object. The intrinsic
strength of the field is set by the mass (gravity) or luminosity
(light) of the object. When distance to the light or gravity producing object
increases, the surface area over which the field acts increases as well. This
effectively weakens the effects of the field felt at the more distant point. The
geometry of a sphere has the increase in surface area be proportional to the
square of the radius. For example, every time the distance increases by a
factor of 2, the effect is reduced by a factor of 4 (22).
ESO 243-49

## ESO 243-49 + ESO 243-49 HLX-1

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Local Superclusters

This spectacular edge-on galaxy is believed to be home to an
intermediate-mass black hole that may have been stripped off of a cannibalized
dwarf galaxy. The estimated 20,000-solar-mass black hole lies above the
galactic plane. This is an unlikely place for such a massive back hole to
exist, unless it belonged to a small galaxy that was gravitationally torn apart
by this one.
Hypervelocity Stars

**Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 Distant Stars

A hypervelocity star is a star that is moving so fast
that it can literally escape the gravitational pull of our galaxy.
It is theorized that these form when a binary star passes too close to the black
hole at the center of the galaxy. One is sucked in while the other is flung
at extreme speeds. They are destined to roam the empty depths of intergalactic
space.
HR Diagram

## HR Diagram

The HR diagram is an extremely important diagram that
compares a star’s luminosity to its color and is used in the cosmic
distance ladder as spectroscopic parallax. This allows us to go
beyond normal parallax distance. Note that temperature is plotted in the
decreasing direction. In 1913, Ejnar Hertzsprung and Henry Russell plotted all
the stars with known parallax and luminosity, and they emerged with a
pattern. There is a main line of hydrogen burning stars, known as the main
sequence. There are two groupings of stars well above the main line, the giants
and supergiants, and a grouping of stars well below the main line, the white
dwarves.
NGC 3021

**Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 The Virgo Supercluster

NGC 3021 was one of the hosts for a few modern Type Ia
supernova observed by astronomers to refine the Hubble Constant. In the 1930s, Hubble actually
made careful observations of Cepheid stars in this particular galaxy.
These Cepheids were used for the supernova here.
Comet 67P

## Comet 67P/Churyumov-Gerasimenko

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 2014

67P hails from the Kuiper Belt. It has a 6.5- year orbit
around the Sun between the orbits of Earth and Mars at its closest, and just
beyond Jupiter at its furthest. It will make its closest approach to the Sun on
August 13th, 2015. The European Space Agency launched the spacecraft Rosetta in
2004. Its mission was to rendezvous with comet 67P; deploy a lander called
Philae to its surface; and escort the comet as it orbits the Sun. Ten years
later, on August 6th, 2014, after getting several gravity assisted velocity
busts, and traveling 6.4 billion kilometer, Rosetta rendezvoused with 67P.
NGC 6537

## NGC 6537 (Red Spider Nebula)

  **Type**
  **Variety**
  **How Far Away is it?**
  **Appears in**
 2013

NGC 6537 also known as the Red Spider Nebula is a bipolar
planetary nebula with material flowing out in two primary directions like my
favorite, the Butterfly nebula. In general, the directions for the flows from
planetary nebula are quite random, but this is not the case for this nebula.
This warm and windy planetary nebula harbors one of the hottest stars in the
Universe and its powerful stellar winds generate waves 100 billion kilometers
high.
How Fast Is It?

## How Fast is it?

  **Type**
  **Variety**
  **How Many Episodes is It**
  **Created**
 December 12, 2015

How Fast is it? is David’s third Videobook that came after
both How Far Away is it?
and How Small is it?
Just like in the first book, he starts in the backyard and moves on up
to the fastest thing possible- the speed of light. Along the way, he
explains what motion is and how both Newton and Einstein
described it. This video book’s main topic is relativity. He also talks
about light cones and how different things change as something approaches
the speed of light, an important concept in the Videobook. He will also talk
about how we came to know about the speed of light and what we did to measure
this important constant. He talks about Galilean Transformations and how
they lead to the Special Theory of Relativity and the General Theory
of Relativity. In the end, he describes black holes and takes
inspiration from Interstellar’s Gargantua (link to all objects
covered in this series)