Welcome to the March night sky. This month marks the official end of winter and the beginning of spring in the northern hemisphere. On Sunday, March 29, the clocks go forward one hour to daylight saving time. This twice-yearly clock change will cease in Europe next year when all the EU countries will keep one time all year around. It’s up to individual countries to choose either standard time or plus one hour.
Early evenings in March have no bright planets visible except for brilliant Venus now at greatest western elongation from the Sun. This planet will be seen high in the western sky at nightfall and it will be the brightest star-like object in the night sky.
The 20th of this month is the spring Equinox and, at this time, the Sun will be seen to rise directly in the East and set 12 hours later directly in the west.
Equinox times are when the Earth’s axis of rotation is at 90 degrees to its orbit, giving the whole planet 12 hours daytime and 12 hours night.
At Equinox time this year, we have visible the March Geminid meteors shower and another minor meteor shower at the same time called the Camelopardalids that have the slowest moving meteors of all known showers at seven kilometres per second. This is still fast, but our Earth’s escape velocity is about 11 kilometres per second so, in fact, our planet is catching up to these meteors in space and overtaking them.
Still visible in the southwestern sky at night fall is the winter constellation of Orion the Hunter. From our point of view, in the northern hemisphere, the red giant star Betelgeuse is at the top left corner of the constellation.
Recently, this star has dropped in brightness by 50%. This is quite noticeable by eye for anybody who is familiar with the night sky. This giant red star is about 400 light years away from us and has long known to be variable.
Red giant stars are thousands of times larger than our Sun and the outer layers are unstable. At the moment, this red giant has blown off a part of its surface larger than our solar system.
This is normal for a red giant but, eventually, these types of unstable stars will explode as a supernova. It could happen anytime, but it will not harm our solar system. Most likely, Betelgeuse has millions of years left, but when it eventually goes supernova, it will be bright enough to be seen in daylight and will leave behind a white dwarf star invisible to unaided eye.
The Moon is at first quarter on the 2nd, full on the 9th, last quarter on the 16th and new on March 24, 2020.
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Clive Jackson is the Director of the Camera Obscura (next to the Castle in Tavira), specialising in education and public outreach.
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To see the March Sky Map click on the pdf link below