Planets change spring sky

Familiar star patterns in the evening sky have been dramatically changed by the presence of two bright planets in the neighbourhood. You could be forgiven for thinking you were seeing double when glancing at Leo where Saturn lies very close to its brightest star, Regulus. And just a short distance away, Mars has distorted the shape of Gemini, making a sharp dog's leg angle with that constellation's leading lights, Castor and Pollux. This star chart shows the planets on April 23. Click on it to enlarge. At the time of posting, Saturn is just a little over 2°, or four moon's widths, from Regulus. At magnitude 0.5, the planet also outshines the star which has a brightness of 1.3. But they make a striking pair sitting at the base of the backward question mark that indicates the head of the celestial Lion. Mars is shining at magnitude 1.1, virtually the same brightness as nearby Pollux, but brighter than Castor, which has a magnitude of 1.6. It lies just half a degree further from Pollux than does Castor, making the new pattern a distinctive one. The Red Planet will not stay close to the Twins for long. It is rapidly heading eastwards and steadily fading following its bright Opposition last December. But it still has a couple of treats in store before it disappears completely into the twilight in the late summer. The next constellation Mars moves into is Cancer, and on May 22, now shining at 1.4, it will move directly in front of that constellation's famous star cluster Praesepe. This is a great cloud of faint stars which together appear as a bright blur in the heart of the Crab. After a couple of nights' lodgings in the cluster, which is also known as Messier 44, Mars heads on its way again. It catches up with Saturn, itself moving eastwards but more majestically, in Leo on July 9. If you then catch them low in the twilight after sunset, they will form a tight pairing, with just two-thirds of a degree separating them. Don't forget you can read more about the Red Planet in Skymania's own special guide to Mars. Chart produced with Starry Night Pro. ©PAUL SUTHERLAND, Skymania.com • Skymania welcomes your comments on our stories! For more space reading, check out the Skymania stores in the USA, the UK, Canada and France. They are powered by Amazon so you can buy with confidence.

Binocular nova flares in Cygnus

A faint star in the Milky Way has exploded and become visible with binoculars in the constellation of Cygnus the Swan. The nova was first spotted on April 10 from Japan by on 10 April by observers Koichi Nishiyama and Fujio Kabashima. They reported it at mag 7.7. Its position is RA: 19h43m01s.96, Dec: +32°19'13".8. This area of the sky is crowded with stars, but the map here should help you identify the nova. Albireo is the famous bright double star at the end of Cygnus's long neck. The position of the nova is marked with a circle. From mid-northern latitudes, such as in the UK, Europe and the USA, this region of the sky becomes observable after midnight. An alert to the nova, first reported in IAU Circular 8934, was published by Sky & Telescope here and will be updated as further information about the nova becomes available. ©PAUL SUTHERLAND, Skymania.com • Skymania welcomes your comments on our stories! For more space reading, check out the Skymania stores in the USA, the UK, Canada and France. They are powered by Amazon so you can buy with confidence.

Look out for a young, slim Moon

Tomorrow evening (6 April) will offer an excellent chance from the UK to view an extremely young Moon, as long as the weather plays ball. With an age of less than 17 hours, just the merest sliver of a crescent will be displayed. However, a combination of circumstances will boost your chances of seeing it. As pointed out in the April issue of the British magazine Astronomy Now, the Moon will stand less than 9° above the horizon at sunset which occurs at around 7.50pm BST. This is higher than usual for such a young Moon, partly because its path through the sky, the ecliptic, is inclined steeply to the horizon in the evening at this time of the year from mid-northern latitudes. But on top of that, the Moon's orbit is inclined 5.2° to the ecliptic and will be at the most northerly point in its orbit in the sector where the thin crescent occurs. Even better, the Moon will be near perigee - the point where it is closest to the Earth and consequently appears slightly larger in the sky. It moves faster when closer to Earth and so will also be at a slightly greater angular distance from the Sun than otherwise. Finding the Moon will still be a challenge a few hours later after sunset over locations in the US and Canada. If you are looking for the Moon with a telescope or binoculars, be careful to wait until the Sun has set or completely disappeared beneath the rooftops. On no account should you ever try to find it while there is any danger of the Sun damaging your eyes. The opportunity of another spectacle involving the Moon occurs on Tuesday evening. It will lie very close to the Pleiades star cluster in Taurus, otherwise known as the Seven Sisters. Observers in the north-east of the US and eastern Canada can see the Moon cover some stars in the cluster - termed an occultation - if it is clear. Picture: An image of the Moon at 19.50 BST as displayed by the computer planetarium program Starry Night. ©PAUL SUTHERLAND, Skymania.com • Skymania welcomes your comments on our stories! For more space reading, check out the Skymania stores in the USA, the UK, Canada and France. They are powered by Amazon so you can buy with confidence.