Starwatch: The April night sky

As our days lengthen, Orion stands further to the SW and W with each evening and has almost completely set in the W by our star map times. This month, however, all the brighter planets are on view, with the two brightest, Venus and Jupiter, at their best in our evening sky. In the wake of the recent solar eclipse, there is also an exceptional total eclipse of the Moon, though not for Europe.

The lunar eclipse comes on the 4th when the Moon transits the N part of the Earth’s shadow. In fact, it barely skims inside the central darker umbral shadow so that totality lasts for only 4 min 43 sec, making this the briefest total eclipse for 486 years. Mid eclipse occurs at 12:00 GMT (13:00 BST) and is best seen from the Pacific and areas around it. Given its position in the umbra, expect the N part of the Moon to remain much brighter.

The eclipse, the first of two total lunar eclipses this year, gets underway at 09:01 GMT when the Moon encounters the fringe of the Earth’s penumbral shadow. However, little darkening will be noticed until it nears the umbra which covers at least part of the disc between 10:16 and 13:45 GMT. The event ends when the Moon exits the penumbra at 14:59 GMT.

Venus, blazing at mag –4.0 to –4.1 in our W sky at nightfall, stands higher and sets later each evening, dropping below our NW horizon after midnight BST from the 14th onwards. Although it is omitted from our chart, it speeds through Taurus, passing below-left of the Pleiades and ending the period between the Horns. Catch the Moon below-left of Venus, and alongside Aldebaran, on the 21st.

Mars, mag 1.4, is sinking lower in the W at nightfall, below-right of Venus, and is likely to be lost by the month’s end. On the 19th, it lies 4° above-right of the Moon and the same distance above-left of Mercury, much brighter at mag –1.4. Mercury sets one hour or more after the Sun from that day onwards, enjoying its best evening apparition of 2015 and ending the month at mag –0.3 and close to the Pleiades.

Jupiter, slow-moving 5° to the left of the Praesepe star cluster in Cancer, is unmistakable at mag –2.3 to –2.1 in the S at nightfall. Our maps plot it in the SW as it moves to set in the WNW in the early hours.

Saturn rises in the SE about 30 minutes after our map times and passes 15-20° high in the S four hours later. At mag 0.3 to 0.1 it is the brightest object low in the S before dawn as it creeps W some 10° above-right of Antares in Scorpius.

April diary

4th 13h Full moon and total lunar eclipse

6th 15h Uranus in conjunction with Sun

8th 14h Moon 2.2° N of Saturn

8th 21h Jupiter stationary

10th 05h Mercury in superior conjunction

11th 06h Venus 2.7° S of Pleiades

12th 05h Last quarter

18th 20h New moon

21st 19h Moon 7° S of Venus

23rd 08h Mercury 1.4° N of Mars

26th 01h First quarter

26th 19h Moon 5° S of Jupiter

30th 22h Mercury 1.7° S of Pleiades

* Times are BST