The night sky in April
For an excellent set of star maps suitable for use with binoculars and small telescopes go to www.binocularsky.com Free to download and Steve Tonkin is an expert in this field.
Also see A Complete Guide to the Solar System and the Night Sky | TheSkyLive for even more details of what is happening as we look up.
Meteors!
There are two meteor showers this month but sadly both are around the full Moon on the 16th April. The fainter ones will be harder to see due to being washed out by the Full Moon.
The first of the showers is the April Lyrids which starts on the 14th and with a weak maximum peak around the 22-23rd April. The Moon will be in its first quarter.
This shower is the result of the Earth passing through the remains of Comet C1861 G1 Thatcher. It is called the Lyrids as the meteors appear from the area of a constellation Lyra (The Lyre). Lyrids – Wikipedia
The second meteor shower is the Aquarids which is a stronger shower starting on 19th April, so close to the Full Moon.and continuing on into early May, reaching an expected peak on May 6th. Eta Aquarids Meteor Shower 2022 (timeanddate.com)
The Aquarids as their name suggests originate in the constellation of Aquarius(The Water Carrier) and are the remains of a trail of debris orbiting the Sun from the famous Halley’s comet. Halley’s comet is not due to return until 2061, so some of our children might see it….
Comets! : 12P/Pons-Brooks
If the weather stays clear we are in for a treat, comet Pons-Brooks will be closest to the Sun on 21st April, less than 1 AU, an AU (Astronomical Unit) be the distance between the Sun and the Earth, Like Halley’s this has a long orbit, 70 years. It could be naked eye but will be easily visible (weather permitting) with binoculars or small telescopes.
Originally found by Jeans-Louis Pons in 1812 at the Marseilles Observatory
To find see the map in the link below of the constellation Andromeda.
Comet 12P/Pons-Brooks | TheSkyLive
It will be best seen at the start of April because of the evening twilight as it is in the west of our skies.The 21st April is currently the optimum date given to observe it. It should be about +4 magnitude and so naked eye obewrvable.
Pons Brook taken at Burnham Deepdale
The Moon
As we enter April the Moon is at its last quarter and the new Moon will occur on April 8th. It reaches full phase on 24th April.
The Full Moon on the 16th is known by various names. In the USA it is the Pink Moon because it occurs when pink flowers such as Phlox are flower in early Spring, it is also known as the Hare Moon as hares are getting active around this month. It has also been called the Egg Moon as April is associated with giving off eggs in pre Christian times.
In the Christian calendar it is called the Paschal Moon and is used to mark the timing of Easter. The Paschal Moon is the first Full Moon after the Spring Equinox. Paschal also means Passover and Easter occurs a week after Passover.
The Planets
Mercury: Is now too close to the Sun to be seen.
Venus: So to is Venus, again invisible to us.
Mars: Can now only be seen as an early morning object as it approaches the Sun with respect to us.
Jupiter: Is crossing from Aries to Taurus and is only to be glimpsed before it sets in the west.
Uranus: I mention this, even though I tend to mention the naked eye planets, as there is an opportunity to see it in the evening twilight on 21st April when it is within 0.5° of Jupiter in a once every 14 year conjunction. The next one will occur in 2037…
Saturn: Is a morning object and hard to see from the Northern Hemisphere.
The Constellations.
Leo is still the dominant constellation of the southern aspect of our night sky.
But this month have a look North. The Plough is high in the sky. Also known as the Big Dipper in North America due to its distinctive shape. In China it was looked upon as a Rice Ladle and was called Bei Dou. In Chinese astronomy the 7 major stars were called the Governors and used as a form of celestial clock as they rotated around the Pole star.
The whole constellation is of course also known as Ursa Major the Great Bear and is much more extensive than just the 7 main stars. Ursa Major – Wikipedia
Two useful stars are Dubhe & Merak which form the side of the dipper away from the handle. Follow a line made by these two stars and you can find the Pole Star, Polaris. This in turn is the tail end of another bear, Ursa Minor or the Little Bear.
The second star in from the handle of the Plough is actually a true binary, two stars rotating around a common centre of gravity. These stars are Mizar & Alcor, their separation is about a light year. In truth it is even more complicated. Mizar has been discovered to be a 4 star system and Alcor a two star system. Mizar Aa and Ab are separated by about 30 million miles and Mizar Ba and Bb 279 million miles, Alcor A is a white dwarf and its partner Alcor B a red dwarf, this pair are separated by between 0.5 & 1.5 Light Years. A Light Year is 6 trillion miles or 9 trillion kilometres, that 6 or 9 with 12 zero’s following it.
A pair of binoculars will reveal Alcor & Mizar as a double, and under very good dark skies conditions I have seen them as a naked eye double, sadly an opportunity slipping away as light pollution continues to encroach on our relationship with the night sky. They are 83 Light Years distant. The other smaller stars need serious optics to resolve them.
The two Bears appear to rotate around Polaris though the night and through the seasons. The constellations that do this are called circumpolar constellations and are more or less permanently visible from our latitude. Others circumpolar constellations like Cassiopeia are are also distinctive with its W shape. More of her in later months when her rescuer from the Kraken, Perseus, makes a better view.
These circumpolar constellations are based on much older observations of the night sky from the Sumerians over 5000 years ago. Passed onto the Mesopotamians then the Greeks and Arabs who wrote them down too.
In China they had a different view of the sky. Polaris represented the Emperor and as on Earth everything had to rotate around him. Their early star maps dating back 2000 years (the first actual maps rather than records) showed not only court officials but palace walls either side of Polaris, palanquins, markets and palace buildings with Princes and Ladies in Waiting.
Frank Dutton (duttonlf@gmail.com)