After the heavier elements and minerals condensed into solid bits of rock, they all orbited the Sun at about the same speed. As you can imagine, collisions of objects moving at the same speed are less destructive than those of objects moving at different speeds. Thus, when rocks orbiting the Sun move close to one another, they stick together more often than they destroy each other.
These pieces gradually grow larger in a process called accretion. Once they are large enough, gravity forces them into spherical shapes. Outside the frost line, temperatures are cooler and hydrogen compounds are able to condense into ices.
Rock and metal are still present in the outer solar system, but both are outnumbered and outweighed by the hydrogen compounds. Thus, the planetesimals that formed in the outer solar system are composed primarily of hydrogen compounds with traces of rock and metal. Terrestrial planets are Earth sized and smaller, composed of rock, silicate, water or carbon. Further investigation will determine whether some of them possess atmospheres, oceans or other signs of habitability.
Or move on to the building blocks of galaxies: stars! What is an Exoplanet? Introduction So far scientists have categorized exoplanets into the following types: Gas giant , Neptunian , super-Earth and terrestrial. Signs of a planet transiting a star outside of the Milky Way galaxy may have been detected for the first time. This intriguing result opens a new window to search for exoplanets at greater distances than ever before. A newly discovered, Neptune-like planet some 90 light-years away might possess a robust atmosphere — and perhaps even a 'tail.
Can we find another world somewhere among the stars that reminds us of our home planet? Will we know it when we see it? Marble in the Sky: the Hunt for Another Earth.
An international team of astronomers discover a trio of hot worlds larger than Earth orbiting a much younger version of our Sun called TOI An infernally hot, star-hugging 'super-Earth' some light-years away just might offer critical clues to how planets like ours are formed.
A new study shows the Roman Space Telescope will unveil more extreme planets and planet-like bodies in the heart of the Milky Way galaxy, thanks to their gravitational tug on the stars they orbit. Conventional wisdom is that the young Sun blew the gases into the outer fringes of the Solar System and that is why there are such large gas giants there. The four inner planets are called terrestrial planets because their surfaces are solid and, as the name implies, somewhat similar to Earth — although the term can be misleading because each of the four has vastly different environments.
Below are brief descriptions of each of these planets based on this information from NASA. Mercury: Mercury is the smallest planet in our Solar System and also the closest.
It rotates slowly 59 Earth days relative to the time it takes to rotate around the sun 88 days. The planet has no moons, but has a tenuous atmosphere exosphere containing oxygen, sodium, hydrogen, helium and potassium. Venus: Venus was once considered a twin planet to Earth, until astronomers discovered its surface is at a lead-melting temperature of degrees Fahrenheit degrees Celsius.
The planet is also a slow rotator, with a day long Venusian day and an orbit around the sun at days. Its atmosphere is thick and contains carbon dioxide and nitrogen. Earth: Earth is the only planet with life as we know it, but astronomers have found some nearly Earth-sized planets outside of our solar system in what could be habitable regions of their respective stars.
Asteroids and Meteors are usually clustered in specific regions in the Solar System "belts" while comets travel alone on often highly eccentric orbits. They are known collectively as "Space Debris. This page will give you a general overview of the different planets that make up our Solar System. You will also find many helpful links to sites with more information about the planets plus Pluto.
So, without further ado, here are the nine planets in order :. To browse a really neat site, which contains information, pictures, and links to lots of other web sites on the eight Planets, click here. Now that you know all about the worlds of our Solar System, click here to learn about planets discovered in other solar systems. After you review these sections, try a few sample questions to test your understanding.
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