Day: November 14, 2016

In a couple of recent Space Sunday reports, I covered the discovery of an Earth-size planet orbiting  our nearest stellar neighbour, the red dwarf Proxima Centuari (see here and here). Red dwarfs  are a class of star which has proven rich ground for planet hunters  –  and this has once again proved the case.

The European Southern Observatory ESO), one of the leading hunters of exoplanets, has  reported the discovery of a “super Earth”, a sold planetary body with roughly five times the mass of Earth. It is orbiting GJ 536, an M-class red dwarf star some 32.7 light years from the Sun. The planet is orbiting its parent once every 8.7 days, at a distance of 0.06661 AU.

The planet was discovered using a pair of instruments operated by ESO: the High Accuracy Radial velocity Planet Searcher (HARPS), mounted on ESO’s 3.6 metre telescope at the La Silla Observatory in Chile, and its sister instrument, HARPS-N, at the La Palma Observatory in Spain. The findings from these instruments were combined with photometric data from the All Sky Automated Survey (ASAS), which has observatories in Chile and Maui, to confirm the existence of the planet.

However, its was no rapid-fire discovery. In all, data from over eight years of observations of the star went into confirming the presence of the planet. Such is the extended period of observations, that the science team were able to gather a huge amount of spectroscopic data on the star. This has revealed it has a rotational period of about 44 days, and magnetic cycle that lasts less than three years. By comparison, the Sun has a rotational period of 25 days and a magnetic cycle of 11 years.

This indicates that GJ536 is, in keeping with most red dwarf stars, exceptional volatile. Such stars are so small, all activity within them is entirely convective in nature, which gives rise to massive stellar flares. So while the new planet may well have “earth” in its description, it is unlikely to be “Earth like”, particularly given its relatively close proximity to its parent star.

Not much more is known about the planet at this point, but this is liable to change over time, and in the meantime, the survey team will continue to gather data on GJ 536 to see if it is home to other planets, such as gas giants further away from it.

November’s Supermoon

The last three months of 2016 are marked by three so-called “supermoons”, and the biggest will be in the night skies on Monday 14th November 2016.

The Moon is in an elliptical orbit around the Earth, at apogee, the point furthest from the Earth, it is between 404,000–406,700 km (252,500-254,187 mi) from Earth. At perigee, the point closest to the Earth, the Moon is between 356,400–370,400 km (222,500-231,500 mi) away. A “supermoon” occurs when the Moon is both full and at perigee, when it can appear up to 14% large in diameter than “normal” full moons.

“Supermoons” aren’t actually rare events; they take to occur once every 14 months on average.  However, the supermoon on November 14th, scores double. Not only will be “just” 356,509 kilometres (221,524 miles) from Earth, pushing it to that 14% increase in apparent size, but also because the Earth/Moon system is approaching the time of year when it is closest to the Sun (which will occur on January 4th, 2017). Therefore, the Moon will be receiving more sunlight than average, further boosting its apparent brightness.

Together, these two events mean that the Moon will be at its “largest” and brightest in the sky since 1948. The next comparable event will not occur again until 2034 – although there will be a further “supermoon” on December 14th, when the Moon again reaches its full phase, but it will be slightly further away from the Earth in its orbit at that time, so not quite as “super”.

Continue reading “Space Sunday: “super Earth”, “supermoon”, and Orion’s future” →