with Dr David Weldrake
March provides us with nights which grow longer, and with warm weather with which to enjoy the evenings. The skies of March are dominated by the bright stars of summer, including orange Aldebaran, red Betelgeuse, blue-white Rigel, white Procyon and white Sirius (the brighest star in the whole sky) all visible towards the north.
White Canopus (the second brightest star in the whole sky) is high overhead and blue-white Achenar lies high in the south-west. Yellow Alpha Centauri, the closest star to the Sun, lies low in the south.
The Southern Cross, the symbol of Australia, lies near Alpha Centauri. Can you use the map below to identify it in the sky?
The colours of the stars are defined by their surface temperatures, with bluer stars being hotter than redder stars. This month allows an excellent opportunity to see the colours of the stars; try comparing Rigel to Betelgeuse with a pair of binoculars.
Jupiter at its best and Venus returns
Last month, the giant planet Jupiter was seen at its best for the year, and continues to be well placed in the evening sky during March. For the last couple of months Jupiter has been seen rising earlier in the night and on the 6 February was opposite the Sun in the sky, rising at the same time as the Sun sets. At that time it was at its closest to Earth, and hence the brightest it will appear for the year. Have a look for Jupiter this month low in the north east after sunset, it can be seen as a brilliant bright yellowish ‘star’.
When you look at Jupiter compare it to the stars nearby. You may notice that the stars twinkle whereas Jupiter does not.
Jupiter is the largest planet in the Solar System, a ball of hydrogen and helium gas so big that more than a thousand Earths can fit inside it. It lies towards the outer Solar System, is the fifth planet in order of distance from the Sun (the Earth is third). Jupiter takes 12 years to orbit the Sun once.
As Jupiter is gaseous, it has no solid surface, and if a spaceprobe was to descend into it, it would fall through the multicoloured clouds, falling into darkness until eventually being utterly crushed by the immense pressures, and never reach any surface.
Everything on Jupiter is huge, with swirling storms of poisonous gases twice the size of Earth wracking the surrounding clouds. The same storms have been seen to last on Jupiter for more than three hundred years. Jupiter spins on its axis once every ten hours, giving the planet among the shortest days of any planet in the Solar System.
Jupiter is a very impressive sight when seen through a telescope. The planet is seen as a fairly large ball, squashed slightly at the poles as it rotates so quickly. The cloud tops of Jupiter are seen as a pair of dark bands that wrap around the planet’s equator, and smaller details of individual storms and colourful cloud features can be seen when the conditions are good.
Jupiter through a telescope is surrounded by four of its largest moons, visible as tiny stars which move around Jupiter from night to night. The four moons are even visible in a pair of binoculars, if held steadily. They cast shadows on the planets cloud tops from time to time, and no two views of the planet are ever the same. Take a look at Jupiter tonight, at its best for the year this month.
The second planet easily seen this month is Venus, which returns to the evening sky, visible as a bright white ‘star’ low in the west after sunset. Venus is the second planet in order of distance from the Sun, and will be seen for several months to come.
The Moon is full on the 6 March, at last quarter (half) phase on the 14th, new on the 21st and at first quarter phase on the 28th.