Exoplanet discovery: Nasa telescope finds seven Earth sized exoplanets around a single star

Nasa's Spitzer Space Telescope has found seven earth like exoplanets in orbit around a single ultracool white dwarf star.


Nasa's Spitzer Space Telescope has found seven Earth like exoplanets in orbit around a single ultracool white dwarf star. The star is known as Trappist-1 and is only 40 light years away, which is very close in cosmic distances. Three of the planets were initially identified as the exoplanets most suitable for life as we know it on Earth, by an international team of astronomers last year. The three planets were discovered by the TRAnsiting Planets and PlanetesImals Small Telescope (Trappist) telescope in Belgium, after which the star was named.

All the seven planets are in an orbit closer to Trappist-1 than Mercury is to the Sun. An individual standing on the surface of one of the planets, can observe geological and atmospheric features on the others. Some of the other worlds would appear larger than the Moon as seen from the Earth. The planets are in the habitable zone of the star, where the temperature is just right for liquid water to exist on the surface. Further observations are needed to confirm if the planets actually have liquid water.

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Image: Nasa.

There are indications that the planets are tidally locked to the star, which means that one side of the planets are in perpetual daylight, and it is always night on the other side of the planet. In this case, there will be a twilight zone between the day and night sides. The weather on these worlds would be more extreme than those on Earth, with strong winds blowing from the day side to the night side, and extreme changes in temperature.

Image: Nasa.

Image: Nasa.

Sean Carey, manager of NASA's Spitzer Science Center at Caltech/IPAC in Pasadena, California says, "This is the most exciting result I have seen in the 14 years of Spitzer operations. Spitzer will follow up in the fall to further refine our understanding of these planets so that the James Webb Space Telescope can follow up. More observations of the system are sure to reveal more secrets." The Hubble Space telescope has also turned its gaze towards four of the planets, to analyse the atmospheric conditions of the alien worlds.

What the surface of one of the planets could look like. ImagE: Nasa.

What the surface of one of the planets could look like. ImagE: Nasa.

Spitzer, Hubble and Kepler will all be used to help Nasa scientists plan for follow-up observations using the James Webb Space Telescope which will launch in 2018. The James Webb Space Telescope can detect signs of water, methane, oxygen, ozone and other components of the atmosphere of the planets.

Water and oxygen support life as we know it on Earth, Ozone protects the lifeforms from radiation, and methane is a byproduct of life. The James Webb Space Telescope can also find out the surface temperatures of the planets, and the atmospheric pressure, key indicators of life.

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The surface of one of the planets can be explored in a 360 degree interactive panorama. Six of the other planets can be seen in a more or less straight line across the sky. An interactive visualisation by Nasa is also available, where the planets can be explored in 3D. In the planet closest to the star, the liquid water is in the twilight zone, as the day side is too warm and dry, and the night side is too cold, frigid and icy. In the planets farther from the star, the liquid water is in the dayside, where temperatures are warm enough, whereas the night side is too cold for liquid water.

The rocky planet in orbit around an ultracool dwarf star. Image: MIT

A rocky planet in orbit around an ultracool dwarf star. Image: MIT

An international team of astronomers have made available data-sets of over two decades of observations, in an effort to crowd source the discovery of new extra solar planets. The scientists cannot go through all the collected data on their own, and are asking for help from the general public. This means that you could come up with the next exciting exoplanet discovery by going through the data at your home.


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