March sky at night — click on the image below to see a larger version

Astronomical attention at the start of the month is focused on Comet Lulin, making its first and likely last visit to the inner solar system. On the 28th the comet lies just to the northwest of the brightest star in the constellation of Leo, Regulus. It is currently brighter than predicted, on the edge of naked-eye visibility at magnitude 5.2, although you will need a very dark sky to stand any chance at all. It helps to have found the comet in binoculars first, and as with any faint and fuzzy astronomical object try to look out of the corner of your eye — the cells there are more sensitive to faint light than those in the centre.

It is visible in binoculars as a faint fuzzy blob, but in telescopes or images it shows both the traditional gaseous tail and a spiky dust tail pointing in the opposite direction. The comet’s most distinctive feature is its unusual green colour, obvious even in large binoculars.

As the month goes on Lulin will fade as it moves quickly through the constellations of Cancer and Gemini. On the 5th and 6th the comet passes two degrees south of the Beehive cluster, M44, although a gibbous moon will threaten to drown out the fainter comet.

Our view of the rest of the solar system is dominated by the planet Venus, bright and obvious in the western sky after sunset at the start of the month. The planet, reaching a brilliant magnitude -4.5 at the start of the month, is a thin crescent and thus a beautiful telescopic sight. As the diameter is also large, at 45 arcseconds, the crescent should be visible in binoculars too. As we approach inferior conjunction on the 27th, when the planet lies between the Earth and Sun, Venus will become increasingly hard to pick out of the twilight, being only 6 degrees away from the Sun on the 21st.

With Mercury, Mars and Jupiter clustered together in the pre-dawn sky, it is Saturn that demands attention during most of the night. At the opposite end of Leo to Comet Lulin, among the lion’s paws, it reaches opposition on the 8th. At magnitude +0.1 it is nowhere near as bright as Venus, but it outshines all the neighbouring stars and this, together with its distinctive yellow tint, should make it easy to find. With the rings almost edge-on, this is a particularly good time for telescopic observers to watch the movements of the planet’s family of moons. In particular, the foursome of Dione, Enceledus, Tethys and Rhea pass in front of the planet in the early hours of March 13.

Away from the solar system, the familiar figure of the Plough, made up of the seven brightest stars in Ursa Major, lies almost overhead in our chart. The two stars on the side of the saucepan farthest from the handle point down towards Polaris, halfway to the northern horizon. The Pole Star is not the brightest star in the sky, but it has been behaving strangely, ceasing the regular series of pulses that led it to be classified as a Cepheid variable.

The other two stars in the “bowl” of the plough point toward the south, toward Regulus at the base of the sickle in Leo. Returning to the Plough, the curve of the tail (including the naked-eye double of Alcor and Mizar) points down to Arcturus at the base of the “Y” of Boötes, the herdsman, and then on to Spica in Virgo. At this time of year we look up and out of the disc of the Milky Way, and in the region of sky between Spica and Leo we find our nearest really large cluster of galaxies. Those with medium or large telescopes can enjoy hopping around this area, while the rest of us focus on the faint fuzzy Comet Lulin, much nearer to home.