Derby and District Astronomical Society
April 2008 Sky Notes
Spring is here, we are now in British Summer Time (BST) and nightfall occurs ever later. The sky this month is dominated in the south by the main
spring constellation of Leo, together with the large but somewhat faint constellation of Virgo. Faint that is apart from the +1.0 magnitude
star Spica which hovers over the southern horizon at this time of year. Both Virgo and Leo are favourite haunts for deep sky enthusiasts
in search of galaxies. Below Virgo and Leo one finds the smaller and somewhat overlooked constellations of Corvus (The Crow) and Crater (The
Cup). Also snaking its way along the southern horizon is the constellation of Hydra (The Watersnake) whose stars are also faint. Arcturus is
now high in the south-east, the Plough is high overhead, and the 'W' shaped Cassiopeia is at its lowest on the northern horizon.
Mercury reaches superior conjunction on the 16th April and is thus too close to the Sun to be visible. However during the last week in April
the planet begins the most favourable evening apparition of the year. The innermost planet will gleam at -1.0 magnitude and be more than 10°
above the western horizon by the end of the month. Unlike Mercury, Venus is too close to the Sun to be observable at all this month. Mars is
a first magnitude evening object in the south-western sky. It continues a steady eastward creep through the stars of Gemini, quite close to
the twins Castor and Pollux. Jupiter is a bright morning object best seen low in the south-eastern sky at around 4 am BST. The giant planet
is joined by a nearly last quarter Moon around 4° below it on the 27th. First magnitude Saturn is visible all night just to the left (3° east of)
the star Regulus in Leo. On the 15th the gibbous Moon forms a right-angled triangle with Regulus and Saturn, lying about 4° below the planet
on that night.
The Lyrid meteor shower peaks around late evening on the 22nd April. The radiant (that point in the sky where the meteors appear to
emanate from) lies 10° south west of Vega near the border with Hercules. The shower can give observed rates of up to 10-15 meteors
per hour. Lyrids are fast and bright, and may leave ionisation trails in the upper atmosphere which can glow for several seconds after
the meteor has passed. Either side of the maximum the shower is active between the 19th and 25th April. Unfortunately bright moonlight around
the maximum will somewhat wash out the shower this year.
The Moon is new on the 6th, at first quarter on the 12th, full on the 20th, and at last quarter on the 28th.
The following charts show the sky as it appears from the UK on April 1st at 23:00 GMT (00:00 BST). The stars will have risen to the same position an hour earlier on April 15th at 22:00 GMT (21:00 BST) and by 21:00 GMT (22:00 BST) on April 30th. The positions of the planets are plotted for the 15th. The charts show the sky looking north, east, south and west respectively. You may have to scroll to see the whole of each chart. The sky maps were generated using Stellarium 0.9.1, which can be obtained for free at http://stellarium.sourceforge.net/.
[Top]