Highlights Scientists have discovered more than 5,000 planets outside of the Solar System, or “exoplanets”. Most stars in our galaxy have at least one exoplanet, and many are unlike any of the worlds in the Solar System. Some exoplanets could be habitable and are prime targets in the search for life beyond Earth.
At a glance: Exoplanets are planets that orbit other stars. Some look like planets in our own solar system, while others are dramatically different. Exoplanets seem to follow the same general rules as the planets in our solar system: Small planets are rocky, big planets are gassy, and the ones in between may be watery. There are other rocky worlds orbiting stars at the right distance to allow ...
We call them exoplanets. Now researchers have found over 5000 confirmed exoplanets, but a relatively small number of these worlds are similar to Earth. Here are the top three worlds that remind us the most of home. Kepler-186f. In 2014, NASA's Kepler Space Telescope discovered the first Earth-sized world in the habitable zone of another star.
How to Search for Exoplanets Even through a powerful ground- or space-based telescope, stars look like tiny points of light. Planets are even tinier and are very difficult to spot next to their bright host stars. Therefore, scientists rely on indirect methods, like looking at the stars themselves for signs that planets might be orbiting them.
New technologies for seeing exoplanets Direct exoplanet imaging, which involves blocking the light from a bright star and resolving the light from a nearby, fainter planet, is an excellent avenue for both reflection spectroscopy and thermal emission spectroscopy.
At a Glance The habitable zone is the not-too-hot, not-too-cold region around a star where liquid water can exist on a planet’s surface. Liquid water is a key ingredient for life as we know it, so exoplanets in their stars’ habitable zones are compelling places to search for life. In certain cases liquid water can exist outside of a star’s habitable zone, such as Europa’s subsurface ocean.
How We Detect Exoplanets: The Direct-Imaging Method In some cases, we can actually see exoplanets next to their host stars and track their orbits. Image: The Planetary Society In November 2008, a group of astronomers using the Keck telescopes announced the imaging of 3 planets orbiting the star HR 8799.
The most Earth-like exoplanets These three planets beyond our Solar System have some important characteristics in common with Earth, like orbiting in the habitable zone of their star.
How We Detect Exoplanets: The Microlensing Method Star gravity makes space bend near it. When a star passes in front of another star, it bends the distant starlight like a lens, making it brighter.
How We Detect Exoplanets: The Astrometry Method Exoplanets and their stars pull on each other. We can’t see the exoplanet, but we can see the star move. The star’s motion compared to other stars shows that an exoplanet exists. Image: The Planetary Society Astrometry is the oldest method used to search for extrasolar planets.
