Fireballs in Jupiter’s Atmosphere

The first of these collisions was observed by A. Wesley from Australia and C. Go from Philippines on June, 3 2010. The second object was observed by three Japanese amateur observers (M. Tachikawa, K. Aoki and M. Ichimaru) on August, 20 that year and a third collision was observed by G. Hall from USA on September, 10 2012 after a report of a visual observation from D. Petersen from USA. Credit: Hueso/Wesley/Go/Tachikawa/Aoki/Ichimaru/Petersen

The first of these collisions was observed by A. Wesley from Australia and C. Go from Philippines on June, 3 2010. The second object was observed by three Japanese amateur observers (M. Tachikawa, K. Aoki and M. Ichimaru) on August, 20 that year and a third collision was observed by G. Hall from USA on September, 10 2012 after a report of a visual observation from D. Petersen from USA. Credit: Hueso/Wesley/Go/Tachikawa/Aoki/Ichimaru/Petersen

The solar system is crowded with small objects like asteroids and comets. Most have stable orbits which keep them out of harm’s way, but a small proportion of them are in orbits that risk them colliding with planets. Read More →

Could Life Have Survived a Fall to Earth?

Asteroid impacting Earth's oceans. Credit: NASA/Don Davis

Asteroid impacting Earth’s oceans. Credit: NASA/Don Davis

It sounds like science fiction, but the theory of panspermia, in which life can naturally transfer between planets, is considered a serious hypothesis by planetary scientists. The suggestion that life did not originate on Earth but came from elsewhere in the universe (for instance, Mars), is one possible variant of panspermia. Planets and moons were heavily bombarded by meteorites when the Solar System was young, throwing lots of material back into space. Meteorites made of Mars rock are occasionally found on Earth to this day, so it is quite plausible that simple life forms like yeasts or bacteria could have been carried on them. Read More →

A Celestial Primer


Understanding Space – Celestial Objects

Download Guide [PDF]

Space is a big, fascinating, and stunningly beautiful place. The universe is full of stars, galaxies, nebulae, planets, moons and much more. Ranging from lifeless rocky worlds such as Mercury to vast galaxies tens of thousands of light-years across, space is home to truly awesome displays of nature. Celestial objects, also known as astronomical objects, comprise the physical entities that make up the universe.

The universe has a hierarchal structure. On the smallest scales of astronomical objects, there is the Earth and our moon. The Earth is part of our solar system of eight planets while, in turn, our solar system is one of billions in the Milky Way galaxy. The Milky Way is one of 54 galaxies in the Local Group, a part of one of many superclusters that make up the universe – everything that exists.

The following guide, roughly in order from the smallest to the largest celestial objects, will help you to understand the scale of the universe, its hierarchal structure and some of the many fascinating things that lie beyond the borders of our world.

1 – Meteors

MeteoriteMeteors are small, rocky debris floating around in the vacuum of space ranging in size from grains of sand to massive boulders. When these enter the atmosphere of Earth or any other celestial body, they are called meteoroids. These bombard us constantly, but the vast majority of them burn up as they descend into the Earth’s atmosphere. This is precisely what shooting stars are – small, burning debris making brief streaks of light in the night sky as they are vaporized. If a meteoroid is either large enough or travelling fast enough to make it through the atmosphere without being annihilated, it will make it to the ground, becoming a meteorite.

Fun Facts about Meteors

  • The largest known meteorite is the Hoba meteorite in Namibia weighing about sixty tons. It is the worlds heaviest naturally occurring chunk of iron and it is believed to have hit Earth’s surface about 80,000 years ago.
  • The best-known meteor showers are the Perseids and Leonids that fall every year in August and November respectively.
  • Some meteorites on Earth originated from Mars, such as the famous Allan Hills 84001 meteorite. This one attracted a great deal of attention due to the presence of possible fossilized remains of Martian bacteria.

2 – Comets

CometComets are small, icy celestial bodies composed of a nucleus, coma and tail. The nucleus comprises the solid bulk of the comet and ranges in size from a hundred meters to a few dozen kilometers. Comets are characterized by spectacular comas and tails, leaving a long trail of bright matter behind them. There are over 4,000 known comets in the solar system and some have been known since ancient times. Many comets have enormous, elliptical orbits around the sun, many reaching maximum distances far beyond the orbit of Pluto.

Fun Facts about Comets

  • Extremely bright comets typically appear no more than once every decade. These are known as the Great Comets and are visible to the naked eye.
  • One of the most famous comets, Halley’s Comet (shown above) may have been the Star of Bethlehem referred to in the Bible. Halley’s Comet makes an appearance every 75 years.
  • The Great Comet of 1811 was clearly visible for almost nine months. It had a coma fifty percent longer than the diameter of the sun – up to 1,000,000 miles long!

3 – Asteroids

Asteroid MissionAsteroids are small celestial bodies of which there are many millions around the Solar System. Asteroids orbit the Sun just like planets do, but they are far smaller. Because of this, they also have negligible gravitational pulls and no atmospheres to speak of. Also, because of their lack of size and gravity, smaller asteroids are irregularly-shaped rather than near-perfect spheres like planets and dwarf planets. The majority of known asteroids are located in the Asteroid Belt between the orbits of Mars and Jupiter. Asteroids are also found in the Kuiper Belt beyond the orbit of Pluto.

Fun Facts about Asteroids

  • An asteroid impact may have been what wiped out the dinosaurs in the Cretaceous-Palaeogene extinction event 65.5 million years ago.
  • Some asteroids have moons (satellites), such as 243 Ida and its tiny moon, Dactyl. Until its discovery, it was thought that only planets had moons.
  • Asteroids may one day be used for mining thanks to their abundance of valuable metals and materials.

4 – Dwarf Planets

Dwarf PlanetDwarf planets are characterized as small planets that are massive enough to have gravitational forces great enough make them spherical in shape. They also orbit the sun directly. Most notably, Pluto is a dwarf planet that was reclassified as such in 2006, until which point it had, since its discovery in 1930, been described as the Solar System’s ninth planet. All of the five known dwarf planets are considerably smaller than the Earth’s Moon. Dwarf planets may also have their own moons. Pluto, for example, has at least five. Dwarf planets are too small and do not have a high enough gravitational pull to be able to retain any more than a trace atmosphere.

Fun Facts about Dwarf Planets

  • Ceres, in spite of being the smallest known dwarf planet, was the first one discovered due to the fact that it is the largest non-planetary body in the inner solar system. It was discovered in 1801.
  • All other dwarf planets are found in the Kuiper Belt extending beyond the orbit of Pluto.
  • In 2015, NASA’s New Horizons space probe will visit the dwarf planet Pluto and take the first ever photos of its surface.

5 – Moons

Europa - MoonMoons, known as natural satellites in the scientific community, are objects ranging in size from tiny asteroids to bodies larger than the planet Mercury. They are gravitationally bound to their host planets, just as the Moon is to Earth. Earth, of course, has only one moon, but some of the other planets in the Solar System have dozens. In total, there are at least 176 moons in the Solar System. Mercury and Venus have none as far as we know, while Mars has two and the gas giant planets have dozens. The first moons discovered around other planets were the four Galilean moons of Jupiter in 1610 by Galileo.

Fun Facts about Moons

  • Many smaller moons are captured asteroids, pulled into the orbit of planets by powerful gravitational pulls. The two Martian moons, Phobos and Deimos are two such moons.
  • One of Saturn’s moons, Titan, is the only moon in the Solar System known to have a thick atmosphere. Because of this and other factors, it remains one of the first places in the Solar System to search for extraterrestrial life.
  • Jupiter has more moons than any other planet in the Solar System with a total of 67! The four largest of these are Io, Europa (shown on right above), Ganymede, and Callisto. Ganymede is actually larger than the planet Mercury. These four moons are known as the Galilean moons.

6 – Planets

PlanetsThere are a total of eight planets in our solar system. Our solar system is comprised of the inner planets and the outer planets. The inner planets, in order of distance from the Sun, are Mercury, Venus, Earth, and Mars. Far beyond the orbit of Mars lie the outer planets, Jupiter, Saturn, Neptune and Uranus. These four planets are gas giants and, thanks to their size and gravitational influence, they each have numerous moons. Gas giants have no known solid surface. The planets of the Solar System vary dramatically. Mercury is a lifeless rock, Venus is a hellish inferno, Earth is home to the only forms of life that we know of and Mars still remains our first candidate in the search for extraterrestrial life either long dead or still present. Since 1995, many hundreds of planets have been discovered orbiting other stars as well. These are known as extrasolar planets.

Fun Facts about Planets

  • There are more than 850 planets orbiting stars other than our own (the Sun), and more are being discovered every week in large part due to the work of the Kepler Space Telescope.
  • Venus is the hottest planet in the Solar System with surface temperatures high enough to melt lead and air pressures as high as those one kilometer under the sea.
  • Water, a key ingredient for life as we know it, is common throughout the Solar System. Water ice is widely distributed on Mars and exists on the Moon, many comets and asteroids, and on various other astronomical bodies.

7 – Stars

StarStars form the center of solar systems, just like our own star, the Sun, is the center of our own Solar System. When you look up at the sky on a clear night, you can start to grasp the vastness of space and the countless trillions of stars in the universe. The vast majority of stars are far more massive than even the largest planets, with the smallest ones being considerably larger the Jupiter and the largest ones being hundreds times bigger than the Sun. The Sun is nothing special as far as stars go and, in fact, there are billions of other stars just like it in our galaxy alone. Just like the Sun, many other stars host planetary systems, some of which may be very much like our own (and possibly home to extraterrestrial life). Stars are classified by spectrum types and are designated by letters. Our sun is a class G star.

Fun Facts about Stars

  • The largest known star is the red hypergiant called VY Canis Majoris. 3 billion kilometers (about 1.86 billion miles) in diameter, the star would extend further than Saturn’s orbit if placed in our Solar System.
  • Our own star, the Sun, is approximately 1.4 million kilometers (nearly 870,000 miles) in diameter.
  • The nearest star to Earth other than the Sun is the triple-star system, Alpha Centauri, 4.3 light-years away. 4.3 light-years equates to approximately 40,000,000,000,000 kilometers. Travelling at 252,800 km/h, the speed of the fastest man-made object, the Helios 2 space probe, would take around 18,000 years to reach it.

8 – Galaxies

GalaxyStars make up galaxies such as our own galaxy, the Milky Way. The Milky Way is one of many billions of galaxies in the known universe. The Milky Way alone contains between 100 and 400 billion stars. Galaxies are vast, gravitationally bound systems containing not only stars, but also nebulae, rogue planets (planets without a host star) and various other celestial bodies. They fall into three broad classes described as elliptical, spiral and lenticular galaxies. Our own galaxy is a barred spiral galaxy characterized by an extremely bright and dense center of stars surrounded by swirling arms. Our own star system lies in one of the arms of the Milky Way orbiting the galactic center at a distance of 26,000 light-years (each light-year is roughly 6 trillion miles). The nearest proper galaxy beyond the Milky Way is Andromeda, about 2.5 million light-years away across a virtually empty void.

Fun Facts about Galaxies

  • The most distant galaxies tell us about the history of the universe. This is because we see them as they were when the light left them – effectively, we are looking back in time.
  • There are only three galaxies visible to the naked eye from Earth. These are the dwarf galaxies known as the Small and Large Magellanic Clouds and the Andromeda Galaxy.
  • There are at least 100 billion galaxies in the known universe, but there may be dozens times more than that.

9 – The Universe

Universe2The observable universe comprises absolutely everything that we can see from Earth. Anything that is further away than the edge of the observable universe is invisible to us due to the fact that the light has not yet completed the long journey to Earth. The furthest we can see is approximately 13.75 billion light-years. The universe is made up of superclusters containing clusters of galaxies such as the Local Cluster where our own Milky Way galaxy is located. What lies beyond the observable universe is not known, although the universe is still generally thought to be finite. The universe is believed to have been created by the Big Bang and has been rapidly expanding ever since.

Fun Facts about the Universe

  • The universe is approximately 93 billion light-years in diameter, but due to the fact that the universe is expanding, we can still see things that are too far away, because we are seeing them as they were when they were closer to us.
  • The largest known object in the universe is the Sloan Great Wall, an enormous wall of galaxies about 1.38 billion light-years in length.
  • The size of the universe and the number of galaxies and stars in them suggest that life-supporting worlds, although clearly rare, could easily number in the billions.

Honorable Mention – Black Holes

Black HoleBlack holes are perhaps the most fascinating and bizarre of all the objects in space. Sometimes, when a star dies, it starts to collapse, the matter of which it is composed becoming more and more densely packed. Eventually, the star is so massive that its gravitational pull becomes so great that the escape velocity reaches the speed of light. When not even light is able to escape the surface, the star becomes invisible and only detectable by its influence on the surrounding area. The black hole is composed of an event horizon that marks the point of no return. Additionally, black holes have a gravitational singularity in the center that is infinitely dense, yet has no volume. At this point, the laws of physics simply break down, making black holes the most enigmatic objects in existence. Black holes are thought to exist in the center of many galaxies, including the Milky Way.

Image Credits: NASA/JPL

Venus, Our Solar System’s Version of “Hell”

Computer generated 3-dimensional perspective view of the "crater farm" on Venus (Magellan press release P-39146).

Computer generated 3-dimensional perspective view of the “crater farm” on Venus (Magellan press release P-39146).

Up until the 1960s, the planet Venus conjured up a very different image in people’s minds compared to today. The brightest object in the night sky after the moon, Venus has been known since ancient times as the morning or evening star. A glance through a telescope reveals a white globe covered in an impenetrable layer of clouds.

The Soviets were the first to launch a robotic space probe to Venus in 1961, the Venera 1. While the first mission failed, both the Soviet Union and the United States remained determined to find out what lay beneath the permanent and all-encompassing thick white cloud cover of the planet. Enthusiasts speculated that the planet, long described as Earth’s twin, would be a hot jungle world teaming with exotic life. Alas, in 1962, the readings from the U.S.-launched Mariner 2 space probe found something quite different. Subsequent missions also confirmed that Venus was, in fact, one of the most inhospitable places in the Solar System. The luxuriant jungle world hypothesis was utterly quashed – instead, Venus was revealed to be the veritable biblical hell.

Welcome to the Infernal World of Venus

Image Credit: NASA/Ricardo Nunes

Image Credit: NASA/Ricardo Nunes

Venus has an average surface temperature of 460°C, hotter than the surface of Mercury in spite of being considerably further away than the sun. This enormous temperature, hot enough to melt lead, is believed to be caused by a runaway greenhouse effect (though opinions vary on this point, and rightly so). Many scientists believe that Venus absorbs (or reflects…depending on whom you ask) much of the sun’s heat and it gets trapped beneath the permanent wall of cloud. The leading theory currently is that the clouds are so thick, that they reflect 90% of the sunlight that hits the planet. This makes Venus a fairly dark and gloomy world despite that fact that it is actually closer to the Sun than Earth.

This burning dark world may already sound inhospitable enough, but that is nowhere near where it ends. Venus also has a crushing atmosphere with air pressures 92 times higher than those experienced on Earth at sea level. This is roughly equivalent to the pressure experiences over 1/2 mile beneath the surface of the ocean. All of the landing modules sent to Venus were ultimately crushed under this immense pressure. And still, it gets worse.

The Venusian weather is truly horrendous. The clouds that completely cover the surface spin more than twice faster than the strongest hurricanes on Earth. Above a dense carbon dioxide layer of the atmosphere are clouds filled with sulphuric acid. In the upper atmosphere, sulphuric acid rains from the skies, although this evaporates long before it meets the surface. Thunderstorms are constant and far more formidable than those experienced on Earth. Bolts of lightning rip through the skies adding to the nightmare.

To add to the hellish climate and atmosphere, Venus is also dominated by volcanoes. Much of the surface is covered by a smooth layer of volcanic basalt and planes of lava. Although there are at least 1600 large volcanoes on the planet, most of them are believed to be extinct. Nonetheless, the amount of sulphur constantly hurled into the atmosphere suggests that eruptions continue to occur in some areas.

Venus also has other properties making it distinctly different from Earth. The most notable is that the length of the Venusian day is 243 Earth days, making the day even longer than the year which is 224.65 Earth days. Even more bizarrely, Venus rotates in retrograde (backwards) motion. Venus has a negligible axial tilt whereas Earth has a tilt of 23°. This means that the planet has no seasons.

Venus almost completely lacks a magnetic field, something that is critical to life on Earth. The magnetosphere on Earth provides protection against cosmic radiation and without it, life on Earth would completely cease to exist. Venus also has no natural satellite (moon), so there are no tidal forces on the planet (except for those from the sun).

Venus was originally thought to be Earth’s sister planet until the true nature of its surface came to light. Nonetheless, Earth and Venus do share a few things in common. Venus has a very similar size and density to Earth. This means that the gravity is very similar. The planet’s composition is also quite similar.

Was Venus Once Like Earth?


Global radar view of the surface from Magellan radar imaging between 1990–1994

There is plenty of evidence to suggest that, billions of years ago, Venus was a more hospitable world than it is today. The Venus Express probe, launched in 2005, made some discoveries that support this evidence. Long ago, Venus’s atmosphere and surface contained hydrogen and oxygen – the two elements that make up water. As Venus lost its magnetosphere, any oceans would have evaporated over millions of years, being sucked out into space. When the planet was young, it could have experienced a brief habitable stage in which very basic forms of life may have formed. On the other hand, the entire surface may have also been extremely volcanically active and covered in molten lava flows rather like Earth in its earliest days before life came into being. However, even if life ever did exist on Venus, all traces of it are likely to have been long lost beneath a completely impenetrable surface of volcanic plains.

Future Human Exploration and Colonization of Venus

Since the discovery of the Venusian surface being so inhospitable, the world’s space agencies have turned their attention to the much more agreeable and promising conditions on Mars. It seems unlikely that any additional probes will be landed on Venus in the near future, although there has been a NASA proposal called the Venus In-Situ Explorer.

Colonization of Venus remains something belonging to the realms of science fiction but, it is not actually quite as outlandish as it may sound. In spite of the horrific surface conditions, Venus is also home to the most habitable place in the Solar System outside of Earth.

At an altitude of about 31 miles above the surface, the Venusian environment is by far the most similar to Earth in the Solar System. Air pressures here are about the same as they are on Earth at sea level and temperatures range from 0° to 50°C. This means that people would not even need to wear pressure suits in such an environment, although they would need to have air for breathing and some degree of protection from the sulphuric acid rain found in the upper atmosphere.

Colonizing this environment is almost certainly possible. Colonies would have to be located in aerostats floating about 50 kilometers above the surface (roughly 31 miles). These aerostats would not be tethered to the surface, but rather, would rotate at the same speed of the clouds, effectively making the Venusian day about four Earth days long. The aerostats would use a breathable mix of oxygen and nitrogen for lift, since these gasses provide far more lift than helium does on Earth thanks to Venus’s heavy, mostly carbon dioxide atmosphere.

Whether humanity will one day colonize Venus remains to be seen but, as our own world becomes progressively overcrowded and increasingly low on resources, such possibilities will eventually need to be taken seriously. I personally would rather take my chances with Mars or even the moon but I’m still a huge fan of Venus nonetheless.

Let’s Explore the Dwarf Planet ‘Makemake’

Astronomers and interested parties have debated back and forth about whether or not Pluto is a planet, but it’s hardly the only controversial object in the sky. Makemake in the Kuiper belt is another object classified as a dwarf planet. Unlike other major astronomical bodies, Makemake is actually named for a Polynesian deity. The name is actually a pun. Makemake is the creator god in the mythology of the inhabitants of Easter Island, and the object was discovered several days after Easter 2005.

The object is 900 miles in diameter and is certainly round enough to be considered a planet. This has caused some people to ask why Makemake isn’t considered to be a planet. In fact, some people might consider the solar system to have as many as 13 planets in its makeup.

While 13 planets might be controversial, Ceres was once considered a planet. Most books call Ceres the largest object in the asteroid belt, but that’s an oversimplification. Some groups call it a failed planet. Had Ceres’ orbit been slightly different, it might have been called a planet between Mars and Jupiter. Some scientists did call it a planet for years, but it’s usually classified as a dwarf planet in modern texts.

Other objects like Haumea and Eris are also candidates for planet classifications in the yes of many astronomers. Some people have even proposed orbital models that make classifying Pluto and Charon as twin planets a distinct possibility. Whether or not these proposals will gain a substantial amount of support among any real number of scientists remains to be seen, but there’s certainly a sizeable body of people who have promoted them.

The term “Trans-Neptunian objects” is sometimes used to describe all major bodies that orbit the sun a measurable distance from Neptune. This classification seems to be based more on political correctness than science, according to some observers. Of course, there are members of the public that reacted to the downgrading of Pluto on purely sentimental reasons. While these mild protests don’t carry much scientific weight, they do illustrate the fact that the public is taking an interest in scientific issues.

Considering that each of these objects may soon be the platform for homesteaders in outer space, people really need to get the classifications in order. Futuristic travel agencies aren’t going to want to debate over what to call their destinations.

Image Credit: International Astronomical Union

What Microfossils Found in Meteorites Can Tell Us

Photo of the martian meteorite ALH84001. Dull, dark fusion crust covers about 80% of the sample. Image Credit: NASA/JSC

While most people associate the term microfossil with the strange ALH 84001 object, there are plenty of other more concrete examples of tiny fossilized organisms. Research conducted with scanning electron microscope equipment has created a wide array of scientific literature regarding these small remains of living organisms. While marine objects don’t necessary have anything to directly do with the biogenic hypothesis of structures in meteorites, they do suggest that it’s possible for some meteorites to have remnants of antediluvian organisms.

This includes shergottite, nakhlite and chassignite meteorites that have come from Mars. It might be ironic that less attention is paid to Venus, when that planet is perhaps more like the Earth than Mars is. In fact, Venus is sometimes called Earth’s twin.

Structures resembling fossils make up the most solid body of proof for extraterrestrials. While research carried out by organizations like SETI isn’t usually accepted by mainstream academia, ALH 84001 showed up on the nightly news. These stories also illustrate the value of finding meteorite material on the Earth’s surface. Space exploration is a noble goal, but the process of recovering meteorites is far easier. It’s something that can be done immediately without any additional technology. That makes it a low hanging fruit for the hands of hungry scientific investigators.


Emmanuelle J. Javaux, Craig P. Marshall, & Andrey Bekker (2010). Organic-walled microfossils in 3.2-billion-year-old shallow-marine siliciclastic deposits Nature, 463, 934-938 DOI: 10.1038/nature08793

Additional Learning Resources:

Stargazing with Open Source Software

While some of you may already run some version of Celestia on your computer, if you’re not, I encourage you to give it a try. Software download directories are regularly listing Celestia’s newer beta releases as they emerge and this particular program has really improved in recent years. Those of you that are using the software currently are likely checking out these releases already. Regular users should probably stick to the traditional version of Celestia, though you might want to check out Celestia Portable if you’re looking for a bit more flexibility in terms of portability. If Celestia isn’t your thing, you might be interested in some of the other planetarium software available out there as well.

Click HERE for links to Celestia software if you’d like to give it a whirl.

Anyone who uses open source software is used to having to download dependencies. Users such as myself spend a lot of time getting software situated just the way we like it. For instance, you might have some stars or trans-Neptunian objects marked so you can easily visit them again. It would be nice to bring these options anywhere you went, right? Portable software allows you to do this very thing. While you still might get stuck downloading dependencies from time to time, Celestia Portable enables you to carry your installation around with you on a thumb drive which is pretty cool. You don’t even have to reinstall it on other computers.

Fans of either the regular Celestia program or its portable cousin might want to have a look at Bing Maps as well. They’ve recently added some astronomy functions, and these can be entertaining for a period of time.

Lawrence Henderson’s Views Examined

Professor Lawrence J. Henderson (1878-1942)

Professor Lawrence J. Henderson is a fairly well known scholar in some circles. This might have to do with the fact that his lecture on astronomy was included in the Harvard Classics (1909-14). That work has now passed into the public domain, which means that readers might start to explore his work once more. Read More →

The Murchison Meteorite Revisited

Piece of the Murchison meteorite

While it took researchers years to prove it, the Murchison meteorite had a number of extraterrestrial organic compounds in it. Four decades is a long time when it comes to space exploration. Forty years is a long time to do anything for that matter. However, this is a serious triumph for science. Read More →

Transit Photometry for Planetary Discovery

Credit: ESA/University of Florida

Transit photometry is a technique astronomers use to detect extrasolar planets. Planetary orbits often force extrasolar bodies to pass between their suns and telescopes on Earth. This causes a drop in the amount of starlight detected by local astronomers. By measuring this drop in light, the relative location of planets can be charted.

Observing the transit pathways that extrasolar bodies take reveals several important pieces of information about them. Size is usually easy to determine from these sorts of studies. Considering that observations can’t be made in person, this might very well be the best way to discover their size.

Studies that take a look at transit photometry data are generally able to calculate the orbital periods of various extrasolar planets. Individuals with an interest in the search for intelligent life might also want to consider what size and orbital have to say about the theoretical habitable zone of another world. Life forms that resemble those found on Earth would most likely be found on planets with similar habitable areas.

Futuristic explorers will quite possibly use the information collected today when trying to select planets for terraforming. Since generational ship missions will need to be carefully planned, collecting accurate data today might save lives tomorrow.