WHAT’S THE STORY?

AMERICA’S National Aeronautics and Space Administration (Nasa) has announced the finding of an Earth-sized exoplanet.

It is the first major discovery of Nasa’s Transiting Exoplanet Survey Satellite (Tess) which is revolutionising our search for planets, and possibly life, elsewhere in the universe.

WHAT’S IT CALLED?

REJOICING in the very sexy name HD 21749c, the newly discovered exoplanet is 52 light years away from us, and is in orbit around a star called HD 21749. It is known that there are two planets in that solar system, and astronomers are speculating that there are more still to be discovered. The first one to be found was named HD 21749b, and is what is known as a “sub-Neptune” large planet. Its discovery was announced earlier this year and Nasa experts were able to say that it has a 36-day orbit. HD 21749c is approximately Earth size and orbits the star in just 7.8 Earth days.

IS THERE LIFE ON IT?

PERHAPS, Jim, but not as we know it. It’s very unlikely as HD 21749 is almost undoubtedly inhospitable to life. With its tight orbit around its star, the surface temperature on HD 21749c is likely to be in excess of 426 degrees C or 800 degrees.

WHAT IS TESS ALL ABOUT?

THE announcement of this discovery is an important development for Tess, because finding exoplanets like Earth is what the satellite is all about.

It has a two year mission to look deep into space, and Nasa hopes to find and measure at least 50 Earth-like planets over the next few months.

Launched in April last year, Tess was sent up to replace the Kepler telescope which was suffering techological failures at that time. Finding HD 21749c confirms that Tess may be our best chance yet of finding a planet that is not only the size of the Earth but also shares our characteristics such as being able to have water and an atmosphere.

WHAT IS AN EXOPLANET?

AN exoplanet is any planet found outside our solar system. Astronomers had theorised for centuries that such bodies existed,and the first serious evidence of one was actually discovered as long ago as 1917, though some claim that English astronomer William Stephen Jacob had provided evidence of a possible exoplanet as early as 1855, when he speculated that orbital anomalies in a binary star system could be due to planets. It wasn’t until the 1950s that a serious search for exoplanets began. Their existence was confirmed in 1988 and in 1992, exoplanets were detected around a pulsar.

The advent of deep space telescopes such as Kepler made the discovery of more exoplanets inevitable. Kepler, it should be said, had already far surpassed expectations by spotting thousands of potential exoplanets before it failed. Nasa’s archives contain either actual findings of, or evidence of the existence of, more than 4000 exoplanets, but Tess’s discovery of its first exoplanet of Earth size could be a game changer in the search for extra-terrestrial life as most scientists accept that life will only be possible on planets like ours orbiting stars like ours at a similar distance as the Earth is to the Sun.

WHAT MORE CAN WE EXPECT?

OVER the course of its mission, TESS will scan the entire sky and return data on about 500,000 stars. That will mean the observed area will be about 400 times greater than Kepler achieved, but Tess won’t be detecting exoplanets as far away. Instead it will concentrate on stars and planets within 300 light years, with scientists able to carry out much more research on those planets. For a closer look at exoplanets, we’ll all have to wait for the James Webb Space Telescope, which is due to launch in 202.

A GOOD DAY FOR NASA?

A VERY good day, for the agency also announced that astronaut Jessica Meir is now set to fly to the International Space Station (ISS) for the first time in September.

More importantly Christina Koch, who is currently on the ISS, is having her stay onboard extended to an expected record-setting flight of 328 days.

In February, 2020, Koch will set a record for the longest single spaceflight by a woman, eclipsing the previous mark set by Peggy Whitson of 288 days in 2016-17. And Nasa also announced the discovery of deep methane lakes on Saturn’s moon Titan, after analysing data from the Cassini mission.