What’s Up! August 2020

A monthly look at astronomical events in the sky and on Earth

Well what a month July was, mainly because of the justified excitement over comet Neowise, but also because Jupiter and Saturn were prominent from early evening. Society members managed to get some photos of the comet, many of which have been posted on our Facebook Chat Group page.


What to look out for in August – a summary

You may have noticed that the nights are starting to draw in. This increase in the length of the night is noticeable in the late evenings in August and heralds the ‘shoulder season’ for astronomical observations – August is the month when one begins to notice the stars again. And with it being predominantly warm, it is probably the month with the best combination of evening comfort and  darkness.

The Perseids meteor shower is the highlight of the month, but with the Moon present it will make viewing challenging. Mars, Jupiter and Saturn will be easy to spot. The Andromeda Galaxy makes a re-appearance and you can also look for the Double Cluster and the Cygnus Star Cloud. Also prominent is the Summer Triangle of Deneb, Altair and Vega.


The solar system

The Perseids

The most prolific of meteor showers, this is a much cherished annual event. Alas the moon will be around to spoil the show by making the meteors difficult to spot. It’s also best to get away from light pollution if you can. The peak is expected between 14:00-17:00 BST on 12 August – during daylight hours! Therefore the best nights for viewing will be 11/12 and 12/13 August. The moon rises around midnight and the best strategy is to try to block it out in some way by positioning yourself so that a building or similar object obscure it. The orientation of the earth in respect of its motion around the sun changes over 24 hours. This means the best time is after midnight when your local position faces the incoming meteoroids, giving brighter trails. Good luck!

The Moon

Full moon is on 4 August, with last quarter on the 12th, and new moon on the 19th. From 2 August the near full moon will join Jupiter and Saturn and this grouping will be visible through the night. You will be seeing the closest celestial object to the Earth near to the furthest that can be easily seen with the naked eye. At 04:30 BST 18 August, 90 minutes before sunrise, and 19 August just after sunset, there’s an opportunity to see a 1% lit waning crescent moon as it rises in the north-east.

Mercury

Only visible early in the month, very low on the horizon in the north-east, one hour before sunrise.

Venus

In early August Venus is a morning planet, rising 3 hours before sunrise. By the 13 August it reaches greatest elongation and is 50% illuminated.

Mars

Mars is moving towards opposition in October, and is in a good position for viewing, reaching an altitude of 43 deg and mag. -1.8 by the end of the month. On 9 August, a waning gibbous moon is only 3 deg apart from Mars and by 11:00 BST the separation will be 1 deg. Okay, this is in daylight, but should still be visible with an optical device.

Jupiter

The planet will be visible throughout the month, but is low in the sky where atmospheric distortions are more intrusive.

Saturn

Close to Jupiter it is also low in the sky. As it has only just passed opposition, it’s worth trying to see how many of its moons you can spot.

Uranus

A morning planet this month, Uranus is at its highest point due south at the end of the month when it will be on the threshold of naked-eye visibility.

Neptune

Another morning planet, Neptune reaching its highest point mid-month and requires at least binoculars to be seen.


Deep sky

The Summer Triangle

In August we can turn our attention to the Summer Triangle and surrounding area. It is formed by the stars Altair in Aquila, Vega in Lyra, and Deneb in Cygnus. During the first week of August this area of sky through which the Milky Way passes on its route northwards is riding high in the south and is peppered with deep sky splendours.  The Astronomy Now chart below shows the best of these. Look high in the south at 2300 BST. Each object is described in the table below.

summer triangle: Lyra, Aquila, Cygnus

The Summer Triangle area of sky  (Chart courtesy of Astronomy Now)

ObjectMagnitudeDescription
Albireo3β Cygni. A beautiful and bright 3rd magnitude double star with amber and sapphire components 35 arc seconds apart. Use a magnification of x30 to see them at their best.
ε Lyrae4.7The famous "double double" comprising two pairs of stars. The pairs are separated by about 3 arc minutes but the components of each pair are only about 2.4 arc seconds apart. This object is a good test for a 4-inch telescope; you'll need a magnification ox x200 or more.
M579The Ring Nebula. Another famous object. It's a planetary nebula that looks like a smoke ring. Although small and faint, it's easy to find, half way between the two stars shown on the chart and will stand a fair degree of magnification. In fact, it is about 4 arc minutes in diameter, nearly six times the apparent diameter of Jupiter.
M277.5The Dumbbell Nebula, another famous planetary nebula. This showpiece of the northern hemisphere never fails to impress, but do try to view it only when the sky is very dark. At 8 arc minutes in diameter, it's easily visible even in binoculars. Not to be missed,

Andromeda galaxy

At 2.5 million light years distance the Andromeda Galaxy is the most distant naked sky object. It lies in the Andromeda constellation.

Andromeda Galaxy, M31
Andromeda Galaxy, M31 (Screenshot from Sky View Cafe)

The Double Cluster

The Double Cluster is two open clusters close together in the constellation Perseus. Both visible with the naked eye, NGC 869 and NGC 884 lie at a distance of 7,500 light years.

The Double Cluster NGC 869 and NGC 884
The Double Cluster NGC 869 and NGC 884(Image from Sky View Cafe)

Cygnus Star Cloud

Part of the Milky Way, the Cygnus Star Cloud, spans 17° from the centre of the cross of Cygnus to Albireo, glows with the granulated light of scores of stars at and near the limit of visibility. Best viewed with a lower power telescope.

The Cygnus Star Cloud, part of the Milky Way
The Cygnus Star Cloud, part of the Milky Way (image from Sky View Cafe)
View of part of the Cygnus Star Cloud, courtesy NASA.

Passes of the International Space Station (ISS)

The ISS is visible on only a few nights in early August and then at the end of the month. See the Heavens-Above web site for more details.


Space News

For up-to-date news on space missions, rocket launches etc. scroll https://www.space.com/32286-space-calendar.html


Remember Oscar Wilde’s famous quote: “We are all in the gutter, but some of us are looking at the stars.” Clear skies and good viewing.

Rob Maclagan with additional text from John Rowland, 1 August 2020

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