Comet Swan in outburst

Comet Swan has become a bright object in the night sky after undergoing a surprise outburst. The celestial visitor was reported to be up to magnitude 4.5 on Tuesday night, 24 October, around five times brighter than was predicted. Comet Swan is now the brightest comet in the night sky for several years but it is not known how long the flare-up will last. The reason is believed to be an eruption within the comet's frozen head, or nucleus, which released a vast cloud of gas as it was warmed by the Sun. At magnitude 4.5, the comet will be fairly easy to spot in a dark sky, providing you know just where to look. It is currently passing between Corona Borealis and Hercules and visible showing a short tail high in the western sky as soon as it gets dark. Its head is shining emerald green - a sign that it contains the poisonous gas cyanogen. Spaceweather.com reports that the delicate tail can be followed for the apparent width of three full moons across the sky before fading away. A map of the sky to help find the comet is at this page on the society's website. Amateur astronomer Pete Lawrence, of Selsey, West Sussex, took the beautiful photo shown here of Comet Swan on Tuesday night following its outburst. ©PAUL SUTHERLAND, SpaceStories.com

Look out for aurora lightshow

Aurora experts are advising that there is a good chance of displays of the northern and southern lights being visible tonight. These natural lightshows happen when highly charged particles ejected from the Sun collide with the Earth's magnetic field. What astronomers call a coronal hole has opened in the part of the Sun facing us and so we can expect a buffeting over the weekend. There is never any guarantee about whether we will see an aurora and the further north in northern latitudes or south in southern latitudes you live, the better your chances. But for those in mid-latitudes, such as southern England, it will be worth keeping your eye on the sky. If aurorae do occur, the Moon will be out of the picture so there is no danger of its light drowning out the show. You should get away from streetlights though. Colourful photographs of displays are time exposures and they will probably appear more subtle to the eye. My alert to the latest possible aurorae came courtesy of the free service offered by the Society for Popular Astronomy. You could also check out Spaceweather.com. The accompanying recent image of the Sun was taken with the Extreme ultraviolet Imaging Telescope, part of Soho, the Solar and Heliospheric Observatory, in space. The coronal hole is the large dark region that can be seen just to the right of centre. ©PAUL SUTHERLAND, SpaceStories.com

Meteors build to a climax

The Earth is beginning to plough through a river of dust left in the wake of Halley's Comet, sparking a meteor shower. The shower is called the Orionids and this year is a particularly good opportunity to view them because moonlight will not be a problem. Best time to watch is after midnight from a dark location away from streetlamps and other lights. The Orionids are so called because the "shooting stars" appear to come from the direction of the club wielded by Orion, the celestial Hunter. It is a point called the radiant, but the meteors themselves can appear in any part of the sky. If you have a clear sky and sit patiently for long enough, you should already be able to spot a few Orionids. But rates will improve as we head towards maximum on Saturday, 21 October. In the early hours of that morning, experts are predicting a maximum rate of 20-25 to occur for an individual observer in ideal conditions. That may not sound very impressive, but a bright meteor is one of the great spectacles of astronomy. Orionids have a reputation for being fast and bright. You can learn more about observing them by visiting the Society for Popular Astronomy's meteor page for October. Interestingly, the Orionids are one of two meteor showers left by Halley's Comet. The other is the η Aquarids in late April and May. ©PAUL SUTHERLAND, SpaceStories.com

Comet Swan is a little gem

Comet Swan has been picked up in the morning sky, as forecast, and is apparently a very pleasing sight in binoculars. Although too faint to be seen with the unaided eye, the celestial visitor is sporting a bright head and distinct tail. As our chart here shows, the comet (2006 M4) is currently passing close to the star Cor Caroli in Canes Venatici, to the south of the Great Bear, Ursa Major. (Click on the map to enlarge it). The Moon is rather bright in the morning sky at present, which will not help observers, but the phase is waning and so things will become easier as the month progresses. You can see a rather nice image of the comet at the Sky & Telescope website. For a more detailed track, you can find an ephemeris here at the website of Jonathan Shanklin, comet section director for the SPA and BAA. The comet was originally discovered by a satellite instrument, one of several automatic devices now scanning the skies. But on Monday, US amateur observer David Levy, of Arizona, continued the grand tradition of finding comets by picking up his 22nd through his 16-inch reflector telescope. He tells Sky & Telescope about his find here. ©PAUL SUTHERLAND, SpaceStories.com