Hertford Astronomy Group chairman Alan Willison continues his guide to getting started with astronomy. This month looking at Mercury and the Lyrid meteor shower.
Hunt the Planet
No matter what you're looking for, the night sky in April is sure to amaze you.
So get out there and enjoy the show!
Mercury Rising
The planet Mercury will be making a great appearance this month.
It is tricky to find but rewarding (in terms of achievement). I have seen it fewer times than I have fingers, so here’s your chance to play catch up.
Mercury is visible most of the month but there is a danger with searching for this planet.
As it is the closest planet to the Sun it is never far from it which means that searching for Mercury with an optical instrument without due caution can lead to permanent blindness.
Wait until the Sun has set completely and then wait at least another 20 minutes. That is because the twilight, where Mercury is situated, will make it almost impossible to find.
After that 20 minutes, start searching the sky for the planet Venus, which will be in the west. Now get your binoculars out and start searching the sky between Venus and where the Sun has set – the sky will be brightest in that direction.
Eventually, you will find Mercury and you can chalk that up as a success.
Mercury is the smallest of the planets in our solar system, being only a bit larger than our Moon.
Even though it is the closest to the Sun it is not the hottest. That honour belongs to Venus whose runaway greenhouse effect has created a much hotter planet.
What else is there to see in April?
The night sky in April is a beautiful sight to behold. The stars are out in full force, and there are a number of celestial events to look forward to.
One of the most popular events of the month is the Lyrid meteor shower. This shower peaks on April 22, and it is known for its bright fireballs. If you're lucky, you might even see a few shooting stars!
Shooting stars are always something to make you look up. Like many things in astronomy, shooting stars are inappropriately named as they have nothing to do with stars.
They are meteors, which are remnants of other celestial objects which have been left in the path of the Earth’s orbit. As the Earth enters this debris field some of them get scooped up into the Earth’s atmosphere. These particles are travelling so fast that they get heated up and appear as a short-lived streak in the sky.
Most meteors burn up in the atmosphere but occasionally one might make it through to land on Earth. This makes it a meteorite.
All the meteors are hitting the Earth almost parallel to each other but rather like the lanes on a motorway they appear to diverge from an apparent centre.
On April 22-23 we have the peak of the Lyrid meteor shower.
The Lyrid meteor shower is a meteor shower that occurs every April. It is caused by the Earth passing through the debris stream left behind by the comet Thatcher.
Lyra is a small constellation in the Northern Hemisphere. It is one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and is one of the modern 88 constellations recognized by the International Astronomical Union.
Lyra is a Latin name that means "lyre." It is associated with the myth of the Greek musician and poet Orpheus, who was gifted with such beautiful music that he could even charm inanimate objects. After his death, his lyre was placed in the sky by Zeus.
Lyra is a beautiful constellation to look at, and it is home to a number of interesting stars. The brightest star in Lyra is Vega, which is the fifth brightest star in the sky. Vega is a white star that is about 25 light years away.
Another interesting star in Lyra is Deneb, which is the second brightest star in the constellation. Deneb is a blue star that is about 1,500 light years away. Deneb is the brightest star in the Northern Cross, a famous asterism in Lyra.
Lyra is also home to a number of deep sky objects, including the globular cluster Messier 56, the planetary nebula Messier 57 (the Ring Nebula – see photo of the month), and the merging triplet of galaxies NGC 6745.
If you are looking for a beautiful and interesting constellation to look at, Lyra is a great choice.
Get your binoculars out
We often recommend that binoculars are one of the most cost effective ways of enjoying astronomy.
Here’s something that you can enjoy on a clear night. Look for the constellation Cassiopeia, which looks like the letter ‘W’.
Starting at the left-hand side number the 5 points of the letter from 1-5. Now, extend a line from number 5 to number 1 and continue the same distance and you will come across a group of stars known as Kemble’s Cascade.
It’s a group of more than 20 stars in an almost straight line over a distance of 3 degrees (about 5 Moon widths). These were discovered by Father Lucien Kemble (1922-1999) with a pair of 7 x 35 binoculars. Even a fairly cheap pair of binoculars will be as good as his were and will show these.
Photo of the Month – The Ring Nebula
Formed when a star reached the end of its life before becoming a white dwarf, the Ring Nebula is a vast expanse of ionised gas in the constellation of Lyra.
If you want to learn more about it just search for M57.
Here are some tips for enjoying the night sky in April
- Find a dark place away from city lights.
- Lie down on your back and look up at the sky. You are permitted a cushion or chair if you prefer.
- Be patient and wait for your eyes to adjust to the darkness – about 20 minutes should be enough.
- Enjoy the view.
Learn more about the cosmos at our next talk on April 12 – 'The New Cosmology or How the Universe Works' – by Professor Andrew Norton.
The meeting is in the Lindop Building at the University of Hertfordshire, Hatfield, and you can get your tickets from our website – https://hertsastro.org.uk. Visitors are most welcome.
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