The March 2017 night sky

Welcome to the March night sky. This is the month of the spring equinox when the sun passes the celestial equator travelling northwards. It marks the end of winter in the northern hemisphere and the beginning of spring, and at that time the whole world has 12 hours daylight and 12 hours night.

On the 26th we have the start of daylight saving time when the clocks go forward an hour over most of Europe. This implies that the Sun will be at its highest point at around 1pm local time, giving us more daylight in the evenings.

This month the Sun is closely followed by the planet Venus in its movement across the heavens, and it will be seen as a so-called evening star for the first two weeks of the month. After that, its orbit carries it between the Earth and the Sun to emerge as a morning star for the last few days of March.

The ancient Greeks called Venus when seen in the evenings as Hesperus, and when seen in the mornings as Phosphorus. It’s not known if they knew it was the same object, but I suspect they did – it’s just that maybe it fitted the mythology better to separate them.

The gas giant planet Jupiter will be rising in the east by 10pm and setting in the west at sunrise. The ringed planet Saturn will rise at around 2am local time and be at its greatest altitude in the sky at sunrise in the direction south. Saturn is rather low in the night sky for observers in the northern hemisphere but its ring system is well visible in any small telescope.

Since 2004, the Cassini spacecraft has been orbiting Saturn and returning amazing images of the planet and its multiple moons. But its mission is expected to end on September 15 when it will be sent out of its stable orbit into one that will take it very close to the rings, and then to enter the atmosphere of Saturn in order to burn up so as not to possibly contaminate any of its moons.

The reasons for this is that it’s not possible to totally decontaminate a large space probe, and any microorganism left could multiply on the surface of a moon especially Titan that has a thick nitrogen atmosphere similar to the Earth’s many billions of years ago. Although, Titan has been landed on by the Huygens probe carried by Cassini, special precautions were taken to sterilise the lander to avoid any contamination.

The Moon is at first quarter on the 5th, full on the 12th, last quarter on the 20th and new on March 28.

By Clive Jackson
|| [email protected]

Clive Jackson is the Director of the Camera Obscura (next to the Castle in Tavira), specialising in education and public outreach.
281 322 527 | [email protected]

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