The Night Sky in August, 2017

The big astronomical event this month is the total eclipse of the Sun which will occur on

August 21st. It will be visible across the USA from the west to the east coast. This is the

only significant land mass where the eclipse can be seen and so it will be a big media

event. It is expected to be observed by more people than any other solar eclipse in

recorded history! The image below shows the path of the eclipse. You can find a video of

it on the following website - http://ryanmarciniak.com/archives/2041

From the UK, we will see a partial eclipse just before sunset. If you look back at my June

newsletter you will find advice on how to look safely at the Sun. You will need a low and

unobstructed view on your western horizon. The eclipse begins around 19:40 BST. The

star chart below shows the sky in the west at that time and you can see how low on the

horizon the Sun is. Note that Mars and Mercury are close to the Sun and Jupiter is visible

in the southwest.

On August 21st, sunset will occur at 20:24 BST. The Full Moon will occur on the 7th and

the New Moon on the 21st which means that conditions should be good for stargazing from

the 21st until the end of the month weather permitting. Surprisingly, the planet of the

month according to the Sky at Night magazine is the ice giant Neptune. The star chart

below shows the sky in the south at 1am BST on August 31st. Neptune is in the south in

the constellation of Aquarius. To the left of it is the circlet which is a famous asterism (an

asterism is a bright pattern of stars which is not one of the 88 official constellations). The

circlet is the head of the fish in the constellation of Pisces. Under dark skies you can see

Neptune with a pair of binoculars even though it is about 2.5 billion miles away! You will

need a 4inch diameter telescope or larger to see its blue disc reasonably well. Neptune will

be at opposition early next month and so it will be even better to observe then. Note that

high in the southeast Uranus is also visible in the constellation of Pisces.

The image on the left below shows you what Neptune and its largest moon Triton will

look like at 1am on August 31st. You may be able to spot Triton with an 8 inch or larger

telescope. The image on the right shows Uranus and its three closest moons!

At about 22:30 BST on August 3rd, you may notice what you think is a bright star close to

the Moon. This is not a star but the planet Saturn as shown in the star chart below. It is in

the constellation of Ophiuchus and just above the “teapot” asterism in Sagittarus.

If you are an early riser then you will find that Venus is a magnificent sight in the

mornings this month. The star chart below shows the sky in the east at 4am on August

19th. There you can see Venus close to a thin, waning crescent Moon in the constellation of

Gemini. To the right of it is Orion and above that the constellations of Taurus and Auriga.

August is the month when the Perseid meteor shower occurs. It will be active from July

23rd until August 23rd but the peak will occur between 15:00 BST on August 12th until

03:30 BST on August 13th. Unfortunately, there will be a bright gibbous Moon to spoil the

view. You can expect reasonable activity between August 9th and 15th and the best time to

observe is near the end of this period. The star chart below shows the sky over Oxfordshire

at 23:00 on August 15th. The radiant of the Perseids will track to the north of Andromeda

and between the constellations of Perseus and Cassiopeia. This where the meteors appear

to originate from although they can be seen all over the sky.

To end on a slightly scary note, a potentially hazardous asteroid (PHA) called 3122

Florence will pass within 5 million miles of Earth on August 31st. Perhaps surprisingly, it

is named after Florence Nightingale! This is the closest it has been since 1890 and it won’t

be this close again until 2500! It is a stony asteroid almost 3 miles wide. You won’t be

able to see it with the naked eye but, under dark skies, you should be able to spot it in large

binoculars or a small telescope. It will approach from the south on August 28th and be

visible in the constellation of Delphinus the Dolphin on the 31st. Even if you can’t see it,

Delphinus is a beautiful little constellation to look at. The star chart below shows the sky

in the south at 21:00 on the 31st. I have highlighted Delphinus at the top of the chart.

Now to the Southern Hemisphere!

What's Up in the Southern Hemisphere?

Unfortunately, there will be no solar eclipse for you this time. However, you are going to

get 11 solar eclipses in total in the 21st Century. The map below shows the eclipses across

the world from 2021 until 2040. The total eclipses are shown in blue.

The map below shows the total eclipses over Australia in more detail. Note that you can

see a total eclipse in two consecutive years in 2037 and 2038. The place to see them both

is near Point Robert or pop over to New Zealand.

You can also get a view of Neptune and Uranus this month. The star chart below shows

the sky in the east over Sydney at 23:00 on August 31st. Note that Uranus is just rising in

the constellation of Pisces. Above it you can see the circlet and to the left is the Great

Square of Pegasus. To the far left you can see the constellation of Cygnus the Swan.

Above the circlet you can see Neptune in the constellation of Aquarius.

You also have brilliant views of Jupiter and Saturn. The star chart below shows the sky

over Sydney at 20:00 on August 15th. The Moon won’t be around to spoil the view then.

You can see Saturn high up on the right near the beautiful objects in Sagittarius. You can

see Jupiter in the bottom left in the constellation of Virgo. If you look to the right of

Saturn and off the star chart below, you will find the constellation of Pavo the Peacock.

Here is a star chart of Pavo and near the centre of it you can see the number 6744. This is

the New General Catalogue (NGC) number of a magnificent spiral galaxy. It is well

placed for you to observe in August. It is about 200,000 light years across which makes it

twice the size of our Milky Way galaxy. It is about 30 million light years away and not

easy to spot. You need dark skies and at least a 12inch telescope to see it in detail but it is

a good target for imaging. Below is one of NASA’s images of it.

Wow! So that’s all for now.

Until next month – happy stargazing and dark skies!

Valerie Calderbank FRAS