What makes a rocky planet

Placing them so close together in a line is for illustrative purposes only. Latest news. Marble in the Sky: the Hunt for Another Earth. The third planet from its star is illustrated here with a narrow band of water between the hot day side and icy night side of the planet.

This artist's concept shows what the TRAPPIST-1 planets may look like, based on available data about the planets' diameters, masses and distances from the host star, as of February Can we find another world somewhere among the stars that reminds us of our home planet?

Will we know it when we see it? Exoplanet Travel Bureau. This set of travel posters envision a day when the creativity of scientists and engineers will allow us to do things we can only dream of now.

Strange New Worlds. Explore an interactive gallery of some of the most intriguing and exotic planets discovered so far.

Historic Timeline. A planetary tour through time. The nebula had a certain amount of angular momentum orbiting the forming Sun. Particles in the spinning disc began to clump together as gravity attracted them to each other. Over a few million years many of these chunks had merged together and there were about 10 9 objects called planetesimals , with diameters of about m.

Over time the planetesimals continued to collide and join together, attracted by gravity. These larger objects, about the size and mass of our Moon, are called protoplanets.

Much of the surface is very old and filled with craters, but there are geologically newer areas of the planet as well. At the Martian poles are polar ice caps that shrink in size during the Martian spring and summer. Mars is less dense than Earth and has a smaller magnetic field, which is indicative of a solid core, rather than a liquid one.

While scientists have found no evidence of life yet, Mars is known to have water ice and organics — some of the ingredients for living things.

Evidence of methane has also been found in some parts of the surface. Methane is produced from both living and non-living processes. Mars has two small moons, Phobos and Deimos. The Red Planet is also a popular destination for spacecraft, given that the planet may have been habitable in the ancient past.

During its lifetime, NASA's Kepler space observatory discovered more than 2, confirmed alien planets — and thousands more possibilities — as of January Kepler ran out of fuel in , but many of its possible planet discoveries still need to be confirmed with follow-up observations from other telescopes.

Using the data from the telescope, scientists calculated that there may be billions of Earth-like planets in the Milky Way galaxy. The spacecraft is designed to look for Earth-size planets that are only a few light-years away from our planet, allowing for quick observations by other telescopes on Earth. As of early , TESS has already discovered a handful of planets; its first confirmed find was in September Thank you!

The formation of rocky planets happens over billions of years, through a process called accretion. As a rocky planet builds-up material through accretion, it grows larger in size and the temperature and pressure in its core rises.