The Night Sky in April, 2017

Spring is here at last! In April, the great constellations of winter set early in the West and the

constellations of Spring and Summer will start to appear in the East. The star chart below shows the

sky in the West over Oxfordshire at 21:00 on April 1st 2017. The planet Venus has looked

magnificent over the winter, but in the middle of March it disappeared from our skies. This is

because it was overtaking us on its inside orbit and was lost in the glare of the Sun. You can see in

the chart below that Mars is in the constellation of Aries and is the only planet visible in the West.

But, if you look low in the West at 19:00 you have a chance to see Mercury at its most favourable.

After the first week of April it also will disappear in the glare of the Sun as it overtakes us.

Above Mars in the chart below, you can see the Pleiades in the constellation of Taurus the Bull.

Near the head of the bull is the Hyades cluster of stars and nearby is the giant star Aldebaran – the

red eye of the bull. Above this is a beautiful crescent Moon. Note that the Messier object M1 – the

Crab Nebula is above the Moon. However, you do need a telescope and dark skies to see it. To the

left of Taurus, you can see Orion which is about to set. To the right of Taurus is the constellation of

Perseus which looks like a chicken wishbone. Below it is the Andromeda constellation and M31 –

the Andromeda galaxy which are both starting to disappear from our skies sadly.

The star chart below shows the sky in the East at 21:00 on April 1st. The planet of the month is

undoubtedly Jupiter and here it can be seen in the constellation of Virgo. Jupiter will be at

opposition on April 7th at 22:00 GMT (23:00 BST). This means that it is on the opposite side of the

Sun from the Earth and at its brightest. Above Virgo and to the left is the constellation of Boötes

which is shaped like a kite. Its most famous star is Arcturus which is a red giant about 69 times the

size of the Sun, its temperature is 4106 degrees K (compared with the Sun’s 6000 degrees) and it is

36.7 light years away. To the left and below Boötes is the constellation of Corona Borealis known

as the Northern Crown. To the left of this is the constellation of Hercules where you can find the

famous Hercules globular cluster M13. The image below shows M13 which can just be seen in a

powerful pair of binoculars but looks magnificent through a 5 inch telescope.

The image below shows Jupiter and its moons at 21:00 on April 1st. You can see the equatorial belts

but the Great Red Spot won’t appear from the back of the disc until about 1 am on April 2nd.

It is interesting to look at the same sky at the end of the month to see how it has changed. Below is

the sky in the West over Oxfordshire at 21:00 on April 30th. Now you can see that Orion, Taurus

and Perseus have almost set. To the right of Mars, you can just see the Pleiades about to set. The

Moon is in the constellation of Gemini – the Heavenly Twins. Near the top of the chart you can see

the stars Castor and Pollux which mark the heads of the twins. To the right of Gemini is the

constellation of Auriga the Charioteer with its bright star Capella. Note that this constellation is

almost the shape of a pentagon if it weren’t for the kink on the right-hand side.

Below is the chart in the Northeast at 21:00 on April 30th. Note that Jupiter is no longer in the

constellation of Hercules. It is now high up in the South in the constellation of Virgo off to the right

of this chart. But now we are seeing the Summer Triangle rising in the East, heralding the approach

of Summer. The brightest star in the Summer Triangle is Vega in the constellation of Lyra. This is

the brightest star in our Summer sky. To the left, you can see the second star of the Summer Triangle

– Deneb in the constellation of Cygnus the Swan. The third star of the Summer triangle – Altair in

the constellation of Aquila the Eagle has not risen yet.

High in the left of the chart you can see the constellation of Cepheus – the King of Ethiopia. This

looks like the gable end of a house. To the right is part of the constellation of Draco the Dragon.

The head of the dragon is a distinctive asterism known as the Lozenge. This can be seen above Vega

with its bright star Eltanin. An asterism is a bright pattern of stars which do not form a constellation.

Another famous asterism is the Plough in the constellation of Ursa Major – the Great Bear.

Note that towards the end of the month, Venus will be out of the Sun’s glare and will re-appear in

our sky as a morning object. It reaches its greatest brightness on April 30th but will be difficult to

spot in the pre-dawn sky. The star chart below shows the sky in the Southeast at 05:00 on April 20th.

Venus has risen in the East in the constellation of Pisces the Fish. It is close to the head of the fish

which is an asterism known as the Circlet. Neptune, a crescent Moon and Pluto are also in this

region of the sky. In the South, in the constellation of Sagittarius, is Saturn. In June, Saturn will

appear in our night sky but sadly will remain low in the South.

The other astronomical event in April is the appearance of the Lyrid meteor shower. This will be

visible in our sky between April 18th and April 25th. About 15 to 20 meteors per hour are expected.

The peak will be on April 22nd and the best time to observe will be between midnight and dawn. The

Moon will be a waning crescent and so won’t spoil the view. Meteors appear all over the sky but, if

you trace them back, they all appear to originate from the same point called the radiant. The

constellation nearest to the radiant gives the shower its name. In the case of the Lyrids the

constellation is Lyra with its bright star Vega. This can be seen in the East at 1am on April 22nd.

Now to the Southern Hemisphere!

The Southern Hemisphere April, 2017

The first star chart below shows the sky in the West over Sydney at 21:00 on April 1st 2017. There

are no planets in this part of the sky for you. At the bottom of the chart, you can just see a little bit of

the constellation of Taurus the Bull which is setting together with the Moon. You can see a few of

the stars in the Hyades cluster and the giant star Aldebaran – the red eye of the bull. The famous

Messier object M1 – the Crab Nebula is above the Moon and is also about to set. Above Taurus is

Orion with the constellation of Lepus the Hare above it. To the right of Orion is the constellation of

Gemini – the Heavenly Twins. The two stars Castor and Pollux mark the heads of the twins. In the

top right, you can see most of the constellation of Cancer which is Y-shaped. There you can find the

lovely Beehive cluster (M44) which is an open cluster of stars about 500 light years away. This can

be seen with the naked eye or binoculars under dark skies but is a lovely sight in a small telescope.

The star chart below shows the sky in the Southeast at 21:00 on April 1st. Here you can see that

Jupiter is in your sky in the constellation of Virgo. To the right is the constellation of Centaurus

with the Southern Pinwheel Galaxy (M83) to the left. To the right, you can see the pointer stars

Hadar and Rigil Kentaurus with the Southern Cross above them.

But your best sight this month can be found in the East at around 22:00 on April 30th. There you will

find the glorious sight of the two great constellations of Scorpius and Sagittarius. In Sagittarius, not

only will you be able to find the large number of Messier objects in that part of the sky, but Saturn

will be there as well. The image below shows you what Saturn will look like at that time. If you are

lucky enough to own a telescope, this part of the sky will be a real feast for the eyes.!

You too will be able to see the re-appearance of Venus in the morning sky. Below is the sky in the

East over Sydney at 06:00 on April 20th. You can see that the Sun is just about to rise with the planet

Uranus. Above you can see Venus in the constellation of Pisces the Fish close to the head of the fish

which is the well known asterism called the Circlet.

I am not sure whether you will be able to see any meteors in the Lyrid shower. Your best chance is

to look in the North around 5am at the time of the peak between April 22nd and 25th. The star chart

below shows the sky in the North over Sydney at 05:00 on April 22nd. There you can see the

constellation of Lyra and its bright star Vega. You can also see Deneb in Cygnus the Swan and to

the right of this is the Great Square of Pegasus. You can also see Venus near the Circlet in Pisces.

That’s all for now. Until next month, happy stargazing and dark skies!

Valerie Calderbank FRAS