What’s Up
The month started with a waning gibbous Moon that becomes new on the 11th, when there is a partial solar eclipse visible only in the far north of the UK, Scandinavia, Russia, Mongolia and China. The first crescent will become visible on the 12th after sunset.
George’s car registration, CAW, is often said to mean “cold and wet”; the implication being that there are clouds to bring the rain! We do need the rain, and it was welcome, but it was a great pity that the longest lunar eclipse of the century was “clouded” out last Friday night. I did get a brief glimpse at about 21:00, along with a very bright planet Mars close by. The next lunar eclipse visible from South Africa will be on 20/21 January 2020.
Mars appeared very bright because it was very close to
Earth - about 57,6-million km - on 31 July. The minimum distance from Earth to Mars is about 54,6-million km and the maximum is about 401-million km, the average distance being about 225-million km.
This is a good month for seeing planets with the naked eye.
Venus shines brightly in the west after sunset. Looking east (to your right), Jupiter is higher up in the north, followed by Saturn and then Mars, brighter than Jupiter but fading quite quickly over the following weeks. On the 14th there will be a pretty asterism when Jupiter is close to a thin crescent Moon. On the 21st, Saturn will be close to a gibbous Moon, with Mars to the lower right.
Whilst the winter sky is great for astronomers, the centre
of our Milky Way galaxy is overhead and few major constellations are visible. Scorpius is overhead with the giant red star Antares at its heart. The name Antares means “Rival of Mars”, since it appears of a similar colour when seen in the sky, but for a very different reason. This is also the only constellation that looks a little like its name implies! A short way to the east is the constellation of Sagittarius, which hides the centre of our Milky Way galaxy. We are unable to see this rich, dense part of our galaxy as it is hidden by gas and dust, but astronomers are able to see this dense region of our Milky Way using sensitive
infrared equipment.
As mentioned before, away from the city lights the Milky Way can be seen stretching from northeast to southwest across our night sky.
The inconspicuous constellation Vela is low at the southwest end and above this is the “landmark” of the southern skies: the Southern Cross and Pointers, which now dominate the southern sky. Even though the two pointers appear to be about the same brightness, Alpha Centauri is the nearest naked-eye star to the Sun, being about 4,3 light years away. Beta Centauri is 120 times further away and about 15 000 times brighter! Alpha Centauri is a double star whose distance was first measured by Henderson, the Astronomer Royal at the then Royal Observatory (now South African Astronomical Observatory) here in the Cape in 1832.
At the other end of the Milky Way is the constellation of Cygnus, which is often referred to as the “Northern Cross”. To the left, or west, of this, the bright star Vega is visible in the constellation of Lyra. Above Cygnus in the Milky Way is the bright star Altair in the constellation of Aquila. Other bright stars are Spica in the west, Archernar in the south-east and Arcturus in the constellation of Bootes in the north-west.