OUR SOLAR SYSTEM
PLANETS
Mercury: Mercury is the smallest planet in the solar system with a radius of 2440 km. Because it is located so close to the Sun, and its mass is so small (relative to the other planets) any atmosphere Mercury may once have had has long since disappeared because of solar winds and radiation, and with such a small mass, Mercury's gravity was not strong enough to retain its atmosphere.
Venus: Venus is the second planet from the Sun, and the closest planet to Earth's size and mass causing it to be referred to as Earth's "twin". Like Eath, Venus does have an atmosphere, though it is composed mostly of carbon dioxide and some nitrogen (whereas our atmosphere is mostly nitrogen and some oxygen).
Earth: Earth still remains the only planet known to astronomers that is capable of sustaining life. Recently, an interest among astronomers has grown in discovering habitable extrasolar planets or exoplanets (planets that orbit stars other than the Sun) where alien life could be possible. Before it was damaged in 2013, the Kepler telescope had discovered over 1000 exoplanets, some of which met certain requirements in order for life to exist (Why Does Life Exist on Earth?).
Mars: The Romans named this planet after the God of War because of its blood-red complexion. The reason behind Mars's colour is in its composition; since the rocks and soil which make up Mars's crust contain high amounts of iron; when it rusts the iron turns into a vivid red-brown colour. Mars's surface is in fact mostly rust or iron oxide. Mars is also one of the only planets ever found by astronomers to contain a form of water - Mars has water in the form of ice located at both poles, in polar ice caps. From data collected by Curiosity (a rover on Mars) scientists have been able to determine that long ago Mars had water for up to 1.5 billion years, before losing 87% of it to space.
Jupiter: Jupiter is the largest planet in our solar system, and is part of the "gas giants" along with Saturn, Uranus and Neptune. Jupiter is made from many different gases (hydrogen and helium) which surround its core, which is made from ice and rock. Jupiter is able to retain the hydrogen and helium gases which surround it since its gravitational force is so great the gases are unable to escape. When you look at Jupiter, you are actually looking at a layer of hydrogen and helium clouds, which are pulled into a spherical shape around Jupiter's core because of its gravity. In order for a rocket to escape Jupiter's gravitational pull, it would have to travel 60 km/sec.
An artist's impression of the our solar system (not to scale).
Saturn: Saturn, like Jupiter, also has a layer of gases surrounding its core. Saturn's core is made from rock, and is larger than Jupiter's. Saturn's gas layer is comprised of hydrogen and helium, though Saturn has less helium than Jupiter. Saturn's most notable feature are its beautiful rings, which are made almost entirely from ice chunks which orbit Saturn.
Uranus: Since Uranus is a gas giant, it is also covered in gases because the planet's enormous mass gives it a strong enough gravitational pull to "hold on" to the gases. Uranus's core is made from icy materials, which is covered with a layer of water, methane and ammonia ice. Finally, the outermost surface is covered completely in an ocean of hydrogen. Similar to Jupiter, Uranus has an atmosphere of hydrogen and helium, but Uranus's atmosphere also contains 2% methane which is what makes Uranus appear blue. Uranus also has rings, which were incredibly hard to detect since they did not reflect light. Astronomers detected them by accident when Uranus's rings blocked the light of a star passing behind it. This is also the method used by scientists to detect exoplanets. Since planets do not reflect light, scientists are only able to detect exoplanets when they pass in front of their host star. They are able to see a slight dip in the light produced by the star, and if it happens periodically, scientists can conclude that a planet is orbiting the star. This is called occultation.
Neptune: Neptune is the third-largest planet in our solar system. As with the other gas giants, Neptune does not have a "surface" - its atmosphere of hydrogen and helium (with traces of methane) transitions to an ocean of water and ammonia. An interesting study conducted at the University of California, Berkeley discovered that Neptune is still in the process of forming and is contracting, causing extreme pressure and heat, that when mixed with Neptune's cold atmosphere causes large storms.
DWARF PLANETS
The term "dwarf planet" was coined in 2006 by the International Astronomical Union (IAU) after the discovery of Eris. According to the IAU, a dwarf planet must:
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Orbit the Sun.
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It has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape.
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It has not cleared the neighborhood around its orbit; and -
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It is not a satellite (a moon).
Sourced from: Dwarf Planets: Interesting Facts about the Five Dwarf Planets. (n.d.). Retrieved December 23, 2015, from http://theplanets.org/dwarf-planets/
Ceres: Ceres is the closest dwarf planet to Earth, and is the only dwarf planet located in the inner solar system (Ceres is found in the asteroid belt). Recent observations from the Herschel Space Telescope, a space-based telescope, have discovered that plumes of water vapour are constantly shooting out of Cere's surface, causing the dwarf planet to lose 6 kg of its mass in stream per second.
Pluto: Pluto was considered the ninth planet in our solar system from its discovery in 1930 until 2006, when it was reclassified as a dwarf planet. With the recent data provided by the New Horizons space probe, astronomers received the first high-resolution photogrpahs of Pluto as well as plenty of new information. Scientists currently estimate that Pluto consists of 50-70% rock and 30-50% ice.
Haumea: Haumea is the least spherical dwarf planet in our solar system because Haumea is the fastest rotating dwarf planet in the solar system. It was first discovered in 2004 by a team of scientists from the California Institute of Technology. It is now believed that Haumea iis made from rocks, with a thick coating of ice.
Makemake: Since temperatures on Makemake drop to lows of -243.2°C, scientists have been able to determine that the surface is covered with methane, ethane (methane and ethane are in a solid form at such low temperatures), or nitrogen ices. Makemake is also the largest object in the Kuiper belt, though it is only the third largest dwarf planet in our solar system.
Eris: Eris is the largest dwarf planet in our solar system - its mass is 28% greater than Pluto's mass. In 2005, after Eris was discovered, scientists were considering naming Eirs the tenth planet in the solar system. However, with the new criteria made by the IAU in 2006 (see above) Eris did not qualify as a planet, and was classified as a dwarf planet instead.
V774104: V774104 was recently discovered by Scott Sheppard and his team in 2015. V774104 is the smallest dwarf planet in our solar system, and the furthest away from the Sun.
Picture from: Dwarf Planets: Interesting Facts about the Five Dwarf Planets. (n.d.). Retrieved December 27, 2015, from http://theplanets.org/dwarf-planets/
Sourced from: Atkinson, N. (2013, February 20). Infographic: What's the Difference Between a Comet, Asteroid and Meteor? Retrieved January 14, 2016, from http://www.universetoday.com/100075/infographic-whats-the-difference-between-a-comet-asteroid-and-meteor/
SPACE ROCKS
Comet: Comets are large chunks of ice, dust and rock that orbit the Sun, in long elliptical orbits. Short-period comets are thought to originate from the Kuiper Belt, whereas long-period comets originate from the Oort Cloud. As comets pass near the Sun their surface begins to sublimate, forming a gas cloud known as a coma. Because of solar winds and radiation, the coma always forms a tail that points directly away from the Sun as comets begin to approach.
Asteroid: Also known as minor planets, these rocky bodies are located in the asteroid belt within our Solar System. Asteroids are leftover debris from the formation of our Solar System, which Jupiter's gravity prevented from forming a planet. Most asteroids are irrelgularly shaped, and revolve the Sun in elliptical orbits while rotating in a "tumbling" fashion.
Meteoroid: Meteoroids are small rocky or metallic debris. They can have a diameter up to about 1 metre, though most are no bigger than a small pebble. Most meteoroids contain nickel and iron.
Meteor: When a meteroid gets pulled into Earth's atmosphere by Earth's gravitational force, it will begin to burn up from the friction of the molecules in Earth's atmosphere as the meteoroid falls through. Commonly reffered to as a "falling or shooting star", this streak of light is actually a meteor.
Meteorite: If a meteor fails to completely disintegrate, the pieces that land on Earth are classified as a meteorite. Meteorites smaller than 2mm are called "micrometeorites".