Three bright stars ride high this month, dominating the major constellations of the spring skies. Leading the way is Regulus in Leo, with Virgo’s leading star Spica to the lower left, with orange Artcurus in Bootes lying above. We are treated to a meteor display on the 21st, some interesting planetary interaction in the dawn skies and Mercury’s best evening display at the end of the month.
April also sees the seasonal change from winter constellations to spring constellations is more or less complete.
The Plough is practically overhead, with the ‘W’ of Cassiopeia is at its lowest. The stars Vega and Deneb, which form two thirds of the summer triangle, are rising in the northeast although they have yet to become prominent.
The main spring stars can now easily be found. In the south is the constellation Leo (the Lion), which looks like a giant backwards question mark, and at its base is the bright star Regulus. To find Regulus use the two pointers in the plough and rather than drawing a line to the North Star, go in the opposite direction.
The plough can also help us find two other bright stars in the spring sky. Using the handle of the Plough draw a curve round and down. This line will reach the bright orange star Arcturus in the constellation of Bootes (the Herdsman). If the line is continued further it will reach the bright blue-white star Spica in the constellation of Virgo (the Virgin).
Mercury will be putting on its best evening appearance of the year. The innermost planet appears above the western horizon just after sunset around 10th of the month. With a magnitude of –1.5 it will be fading all the time. Mercury quickly moves upwards to pass Uranus on the 17th April. It is at its greatest separation from the Sun on the 29th when it will have dimmed to magnitude +0.4 and will be setting as late as 10.30pm. On the last two nights of the month Mercury will be right next to the Pleiades star cluster.
The undisputed queen of the morning sky at a resplendent magnitude of –4.2. It rises above the horizon around 5am. At the start of the month Saturn and Mars lie just to the right of Venus in the constellation of Capricornus, at magnitude +0.9. As the month progresses, Venus and Mars both move to the left in the sky.
As stated at the beginning of the month Mars and Saturn are very close together in the south eastern sky. At magnitude +1.1 the red planet passes just 20 arc minutes under Saturn on the 5th April. By mid month Mars rises above the horizon at 4.40am.
From the 7th of the month you will be able to spot Jupiter rising in the east around 5.30 am. It is well to the lower left of Venus in the constellation of Pisces. The gas giant is second only to Venus in brightness, with a magnitude of –2.1. The two bright planets are converging, with Jupiter lying just to the left of the morning star before dawn on 30th of the month.
As stated at the start of the month Saturn and Mars can be found to the right of Venus. Saturn will brighter than Mars at magnitude +0.9. On the morning of the 5th April Saturn will be 20 arc minutes above the red planet. By mid month the ring world will be rising above the horizon twenty minutes before Mars at 4.20am.
Faint Uranus is the only planet keeping watch over the evening sky at the start of the month. With a magnitude of +5.9 it is hardly visible to the unaided eye. It can be found in the constellation of Aries and sets below the horizon around 9.30pm.
Located in the constellation of Pisces, Neptune rises above the horizon about 5.30am. The outermost planet is close to Jupiter on the 13th and Venus on the 28th. It will be difficult to spot this dim world, at magnitude +7.9; against the bright twilight glow.
Located low down in the south west in the constellation of Sagittarius. At magnitude +14.45, this distance world rises at 2.35 am and will be visible until sunrise.
The largest object in the asteroid belt can be located in the constellation of Taurus this month, at magnitude +8.9. It will be setting about midnight.
The first major meteor shower since January can be seen this month. The April Lyrids occur on the night of April 21st/22nd when about 10 meteors per hour can be seen. The Lyrids are so named because they appear to come from the constellation of Lyra (the Lyre). The meteors are tiny grains of dust left over from comet Thatcher 1861, as they burn up in the Earths atmosphere.
Phases of the Moon for April:-
New Moon 1st April
First Quarter 9th April
Full Moon 16th April
Last Quarter 23rd April