Earth sized planet found orbiting around distant star
In 1992 history was made as astronomers, Aleksander Wolszczan and Dale Frail, had concrete evidence for the existence of the first exoplanet, a planet orbiting around another star (or pulsar in this case) in our galaxy. It has been long theorised that other planets existed outside of our solar system, as early as the sixteenth century, the Italian philosopher Giordano Bruno proposed that the fixed stars we see in our sky are similar to the Sun and are similarly accompanied by planets. Giordano Bruno was a passionate supporter of the heliocentric model of the solar system, that the planets orbit around our Sun which is at the centre of the solar system, this wasn’t widely accepted to be fact until the early 1700s. It is this now basic knowledge that gives astronomers their methods of finding more exoplanets.
As of April 2020, there are now 4,144 confirmed exoplanets in 3,074 systems, with a further 5,094 candidates awaiting confirmation. The majority of these planets were found by the Kepler Space Telescope, which spent nine years monitoring distant stars for transit signals, where a planet passing in front of a star causes a dip in its brightness, the same as walking in front of a torchlight but on a much larger scale. This requires the orbital plane of the planet to be in line with the Earth, despite this, the rate at which the Kepler Space Telescope discovered planets was incredible and in several cases, multiple planets have been observed around a star. Assuming there are 200 billion stars in the Milky Way, it can be hypothesized that there are 11 billion potentially habitable Earth sized planet´s in the Milky Way.
Now even two years later after the Kepler Space Telescope retired from service its data is still being processed and exoplanets are still being found. This week for example, an intercontinental team of researchers found a signal in Kepler‘s archive that escaped discovery previously. This signal shows that there is a second planet orbiting Kepler-1649, a dwarf star located 302 light-years away. What is particularly exciting about this discovery is that it’s the most Earth-like planet ever found by Kepler in terms of size and temperature! The team established that the planet was 1.06 Earth masses and collects about 75% as much light as our planet does from the Sun (meaning it might have similar temperatures). Because the host star is a red dwarf type it is much smaller than our Sun at around ¼ the radius, this means the exoplanet’s orbit is much closer than the Earth’s orbit of the Sun and it only takes the planet 19.5 days to complete one orbit. Although this exoplanet could potentially sustain water on its surface, due to the type of star it orbits, it is thought that the chances are unlikely and even more unlikely of it hosting life. Scientists believe that such stars are prone to frequent solar flare activity, and that such flares may have stripped the exoplanet’s atmosphere and hindered the prospect of life.
So, the search for the perfect ‘Earth-like’ exoplanet continues with NASA’s Transiting Exoplanet Survey Satellite (TESS) mission. The TESS Mission is designed to survey over 85% of the sky (an area of the sky 400 times greater than covered by Kepler) to search for planets orbiting around nearby stars (within ~200 light years). TESS stars are characteristically 30-100 times brighter than those surveyed by the Kepler satellite. Planets detected around these stars are consequently far easier to characterise with follow-up observations, resulting in more accurate measurements of planet masses, sizes, densities and atmospheric properties.
At the Aurora Borealis Observatory we wonder if there is an exoplanet out there like the Earth that have their own displays of the northern lights. We know the processes that create these magical displays above our resort in Senja, Norway, has been observed on the largest gas planets in our solar system, Jupiter, Saturn, Uranus and Neptune. That allows us to wonder if there is another world that is fortunate enough to enjoy this unforgettable experience. Are there a earth sized planet to discover ?