This can help them figure out the size of the planet. See that little black circle? That's Venus transiting our Sun back in By studying the time between transits, astronomers can also find out how far away the planet is from its star. If a planet is just the right temperature, it could contain liquid water—an important ingredient for life.
So far, thousands of planets have been discovered by the Kepler mission. We now know that exoplanets are very common in the universe. And future NASA missions have been planned to discover many more! What Is an Exoplanet? The Short Answer:. More about exoplanets! Searching for other planets like ours What is a barycenter? Therefore, scientists rely on indirect methods, like looking at the stars themselves for signs that planets might be orbiting them. Through increasingly sophisticated technologies, we can not only figure out basic exoplanet traits like mass and diameter, but whether a world is solid or gaseous or even has water vapor in the atmosphere.
One of the main goals of exoplanet research is to planets that resemble Earth. Generally speaking, this means the planet might have liquid water and an atmosphere that could support life as we know it.
Life on other worlds may be unrecognizably different from what we know here on Earth, and even life on our planet is extraordinarily diverse. But it makes sense to start by looking for worlds that resemble our own. Scientists call the region around a star where liquid water can exist on the surface of a planet the habitable zone: not so close to the star that water all evaporates, and not so far from the star that it all freezes.
We can tell if a planet is in the habitable zone based on the distance of the planet from its host star and the temperature of that star. There could be as many as 40 billion planets in the habitable zone of stars right here in our Milky Way galaxy. Imagine what our Sun and Earth would look like from a few hundred light-years away. Using our present-day technologies, you might be able to determine that Earth is a small, rocky planet that sits in the Sun's habitable zone.
Next, you could look for signs of water in the Earth's atmosphere, to rule out it wasn't a dry, desert planet like Mars. Our current technologies are just barely capable of doing this , while upcoming ground and space-based observatories will be able to do it even better. By then, you might be able to conclude Earth was habitable.
But to tell if there was actually life on the surface, you'd need to find gases in the planet's atmosphere like ozone that are possible byproducts of life. Some planets, like HD b, are too hot to have liquid water, while others are too cold. Two planets that orbit in the habitable zone around their host star are Kepler e and f [ 4 , 5 ].
Both planets are a bit larger than the Earth. Astronomers hope to use the soon-to-be-launched James Webb space telescope to measure the masses of these nearly Earth-sized worlds, to figure out if they are rocky or gaseous, and therefore whether or not they have surfaces and possibly water and would be good hosts to life as we know it.
As we discover more and more planets, we will surely need more astronomers like you to help us figure out which ones are the most promising hosts for life. The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Detection of planetary transits across a sun-like star. The NASA exoplanet archive: data and tools for exoplanet research. Most 1. Kepler a five-planet system with planets of 1. Science — The effect of orbital configuration on the possible climates and habitability of Keplerf. Astrobiology — Share on Facebook. Core Concept Published: January 8,
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