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Posted by portugalpress on November 02, 2017

Welcome to the November night sky. This is the month in Northern Europe of the first night frosts as winter approaches.

Visible over in the east as darkness falls, the grand constellation of Orion is now on the horizon and by midnight it will be well up and closely followed by Sirius, the brightest star in the night-time sky.

Sirius is relatively close to the Earth at nine light years away and it is about 25 times more luminous than the Sun. This star is relatively young at 250 million years and this is only 5% of the age of the Sun, so there is little chance of any inhabited planets orbiting Sirius. Also, to make things more difficult, Sirius has a massive but physically small white-dwarf star in a close orbit around it and this could disrupt the formation of a stable planetary system.

This white dwarf started out as a giant star, larger and more massive than Sirius, but, as a consequence of this, it quickly evolved into a red giant and then blew off into space most of its atmosphere to leave only its core that we now see as the super-hot white dwarf. All this violent activity would have made the Sirius star system a risky place to be during its early years.

To make up for the lack of bright planets visible in the night sky this month, we have two notable meteor showers. The first is called the Taurids on the night of the 5th, the second is the famous Leonids on the night of November 17.

The Leonids can be spectacular, with thousands of shooting stars visible, although this usually happens every 33.3 years when the Earth crosses the old orbit of comet Tuttle. The last big Leonid shower was in 1999 when I personally saw a total of more than 3,000 meteors during the evening of the 17th. In theory, this year will not be anywhere near as good but is still worth watching out for.

The Moon will be full on the 4th, last quarter on the 10th, new on the 19th and first quarter on November 26.

By Clive Jackson
|| features@algarveresident.com

Clive Jackson is the Director of the Camera Obscura (next to the Castle in Tavira), specialising in education and public outreach.
281 322 527 | info@torredetavira.com www.torredetavira.com

To see the May Sky Map click on the pdf link below

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