Palácio Fonte da Pipa (by Sara Alves) 3.JPG

The November night sky

By Clive Jackson [email protected]

Clive Jackson is the Director of the Astronomical Observatory of Tavira (Sitio do Malhão, Tavira) and the Camera Obscura (next to the Castle in Tavira), specialising in education and public outreach.

Welcome to the November night sky. This month is still dominated by the planet Jupiter.

This planet is visible all night long in the constellation of Pisces. The four large Moons of Jupiter are easily visible with any optical aid. On November 9 the full Moon will be very close to Jupiter.

The Leonid meteor shower has its traditional peak of activity at midnight on the 17th. These meteors are dust left over from the comet Tuttle. Historically, this meteor shower has been good and sometimes spectacular.

But, for the year 2011, it is not expected to be anything special, but it might be worth keeping a lookout on the night of the 17th.

Half-an-hour after sunset on November 10, we get our best chance to see the elusive planet Mercury. If you look over in the southwest you will see the brilliant planet Venus low on the horizon. This will be easy, but just below Venus and much fainter you should see a little star-like point of light and this will be the planet Mercury. This planet is not much bigger than our own Moon but it is much more massive and the surface gravity is nearly 40% of our Earth’s.

As Mercury is the closest planet to the Sun it might be thought that it would be exceptionally hot, the fact is that it rotates very slowly with one Mercurian day being about 176 Earth days long, so the nights can last over 2,000 hours and this allows the temperature to drop to around 170 degrees below zero just before sunrise.

Also, the Sun rises very slowly and the terminator, which is the diving line between night and day, moves over the surface of Mercury at only about 6 miles per hour, the speed of a fast walk, so it would be possible to outrun the Sun on Mercury.

Also at the poles of Mercury there are deep craters where the rays of the Sun never reach and they are in permanent darkness. It is suspected that they are full of ice with temperatures of 200 degrees below zero.  So frostbite on the closest planet to the Sun is very possible.

The NASA space probe called Messenger successfully entered orbit around Mercury in March of this year and it is on a mapping mission designed to last 12 months. On November 26, just after sunset, the very thin crescent Moon will be on the western horizon close to Venus and Mercury.

The Moon is first quarter on the 2nd, full on the 10th and last quarter on the 18th and new again on November 25.

Clive Jackson is the Director of the Camera Obscura (next to the Castle in Tavira), specialising in education and public outreach. Tel 281 322 527, Fax 281 321 754, Email [email protected] or visit