Astronomy News for August – from John Saunders


On August 11th this year the planet Saturn will be at its equinox with the Sun and it will remain like this for up to a year. Because of the enormous shadows of the planet falling across the ring system and particularly as they will fall on Saturn’s moons, the Cassini spacecraft, which has been in orbit around Saturn for the past 5 years, will spend an entire year studying several of Saturn’s moons such as  Enceladus, Titan (Saturns’ largest moon), Rhea, Helene and Dione in particular. We can expect some spectacular photos to be seen and fascinating information that will better help to understand the structure of the ring system. It is being called -’The Biggest Show on Saturn ever seen’.

When a star begins to die, it can grow to an enormous size and is then called a Red Giant. Our Sun will one day become a red giant, expanding outwards to be so large it will take in the entire orbits of Mercury, Venus and Earth before eventually exploding into a supernova. The star Betelgeuse in the constellation of Orion is such a star. It is so large that its diameter is almost 5.5 times the distance between the Earth and the Sun. Try to imagine something so large. It is difficult to comprehend.

However Betelgeuse or as it is often called, Beetlejuice (pictured above, top left) is getting smaller. Its diameter is now 15% per cent smaller than when it was last measured in 1993. No-one knows why it is getting smaller but further studies are being made. Remember it is a dying Star but it is still the 9th brightest star in the night sky. It is chucking out 135,000 times more energy than the Sun. It is 640 light years away from Earth.

Just imagine, the light of Betelgeuse that we see now was the very same moment 640 years ago when the Plantagenet King Edward III was on the English throne in the year 1340. The light of the star sped away at 300,000 km’s per second, on through the Stuart times and King Henry the VIII and his 6 wives. On and on the light sped still going at 300,000 km’s per second through the times of Christopher Columbus’ discovery of the New World, on through Napoleonic Wars, Boer War, First and Second World Wars. Still, on and on and still at light speed. So we see it now as it was all those centuries ago. There is a belief that during that time it could have exploded in a supernova which we haven’t yet seen. If it has become a supernova, it would shine as brightly as our Sun for a few weeks and this could of course occur any time in the next 640 years.

Orion and Betelgeuse cannot be seen from the southern hemisphere right now but The Hunter, as it is known will reappear as the most beautiful constellation in the southern night sky around December.

Remember we in the southern hemisphere see it upside down.

Information extracted from Astronomy Now magazine.

Leave a Comment

Your email address will not be published. Required fields are marked *