Seven Earth-like exoplanets in a single solar system

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Astronomers have identified more than 4,700 potential exoplanets in the last few decades, and you can add seven more to the list today. NASA has announced the discovery of an amazing planetary system in orbit of a nearby star consisting of seven Earth-like planets in the habitable zone. The star known as TRAPPIST-1 is a mere 39.13 light years away. It’s much smaller and cooler than our sun, but all seven of those planets are clustered in very close, which would make for an incredible view.

TRAPPIST-1 is what’s know as an ultra cool dwarf star. These objects have a temperature under 4,400 degrees Fahrenheit (2,430 degrees Celsius) and extremely low mass (for a star). TRAPPIST-1 only about 8% the mass of our sun. So, it doesn’t put out nearly as much energy, but it will remain in this state for up to 4-5 trillion years, much longer than our sun. It can still have habitable worlds if they’re orbiting close enough, and TRAPPIST-1 appears to have plenty of them.

This illustration shows the possible surface of TRAPPIST-1f, one of the newly discovered planets in the TRAPPIST-1 system. Scientists using the Spitzer Space Telescope and ground-based telescopes have discovered that there are seven Earth-size planets in the system.

Credits: NASA/JPL-Caltech

View this and many more images, as well as several videos, in an extensive multimedia gallery highlighting this discovery.

Three probable planets were spotted in orbit of TRAPPIST-1 in 2016 by astronomers using the TRAPPIST telescope in Chile. This was exciting enough to warrant a quick follow up by the Spitzer Space Telescope — TRAPPIST-1’s small size and low temperature was ideal for study with Spitzer’s infrared instruments. Using this telescope, astronomers were able to monitor for the transit of the planets in front of TRAPPIST-1. These transits happen frequently as the planets are all in very close orbits. Spitzer was used to confirm two of the planets, but it found that one of the previously identified objects was actually three different planets in similar orbits. It also picked out two previously undetected planets in the TRAPPIST-1 system for a total of seven. If you were on one of these planets, the other planets in the solar system would appear larger in the sky at times than the moon appears from Earth (see above for an artist’s rendering).

The truly amazing thing is that all seven planets are in the same size and mass range as Earth. Astronomers were able to determine the size of all seven, which range from 0.76 to 1.13 times that of Earth. Mass was determined for most of them, which is between 0.41 and 1.34 timer Earth. Three of them are in the habitable zone.

The Hubble Telescope is currently being used to scan the exoplanet atmospheres for signs of hydrogen gas. None has been found as of yet, meaning they’re most likely rocky worlds that could have liquid water on their surfaces (three of them are prime candidates based on their location). Hubble will soon be used to look for signs of water and methane on these planets, but that’s pushing the capabilities of the aging telescope. NASA hopes to learn more when the James Webb Space Telescope is online. It’s scheduled to launch in 2018 and will be capable of making more detailed examinations of dim objects like exoplanets.

We don’t yet know if life could exist on these worlds — they would be blasted with ultraviolet radiation so close to their star. TRAPPIST-1 will surely be heavily studied in the next few years, so maybe we’ll find out mmmmmm..........  

There is, then, some positive evidence in favour of the existence of a planetary body in connexion with this system.

In 1855 Capt. W.S Jacob of the East India Observatory in Madras, India, finds orbital anomalies in the binary star 70 Ophiuchi that he claims are evidence of an extrasolar planet - the first exoplanet false alarm. The "discovery" begins a 140-year period of other exoplanet discovery false alarms, but no actual planets are discovered......