Watch out for cosmic fireworks!
- Credit: Torbay Astronomical Society
Stargazing with John Stapleton from Torbay Astronomical Society:
You may have seen the animations of the two neutron star/ black hole mergers in the news recently, but did you realise that both films were artists impressions being modelled by computer?
In fact, no visible light was recorded at all!
The discoveries were made by reviewing data collected by Gravity-Wave Telescopes in 2010.
The importance of the discovery being the first examples of this type of collision ever recorded.
Furthermore, both events occurred at a distance of, approximately, one billion light years.
A light year is the distance light travels in one year at 186,000 miles per second.
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So 6 million, million miles a year.
This also means that the events took place over a billion years ago and the invisible gravity waves have only just reached us.
Nearer to home, an event recording the death of a massive star, called a supernova, was also reported last month - less massive stars die in an event termed a nova.
These events are more common, especially in distant galaxies.
Our own galaxy is overdue such an event.
Dedicated amateur observers, who have a detailed mental picture of the night sky scour the heavens looking for anything that is not already on their mental map, so a general overview of the sky is essential.
Professional astronomers, who often specialise in a single field or object, do not have this.
It is my pleasure be a friend and colleague of Ron Arbour who has made 33 supernova discoveries from his home observatory in Hampshire.
Even closer to home, within the Earth’s atmosphere, we see shooting stars.
These are caused by the burning up, due to friction, of small particles that orbit the Sun in the wake of comets and are swept up by the Earth’s atmosphere as it intersects that orbit.
August sees the brightest and often, most spectacular, of the annual meteor showers; the Perseids – so called because they appear to radiate from a point in the constellation of Perseus.
The maximum of activity takes place on the night of August 12/13 when up to 60 meteors an hour may be seen.
This figure is standardised by assuming the radiant point will be directly overhead so that meteors travelling in all directions can be seen.
However, in actuality the radiant is relatively low in the north-eastern sky until the early hours, and this is the best time for observation, although it is worth looking out from the moment it gets dark, after 22.30.
Observing meteors could not be simpler.
The only necessary bit of equipment is a garden recliner or deck chair so that you can lay back and look at the sky about 40 degrees above the horizon comfortably.
If you want to make a record, simply count the number of meteors you see.
You can also note the direction of travel, the duration, which will typically be seconds, and anything unusual such as colour, faint trails, or sound.
This shower is known for producing occasional, bright fireballs.
The term 'Glorious Twelfth' therefore has a different meaning to astronomers than to the shooting fraternity.
The Star Chart
The sky will look like the chart on August 7 at 9pm and again on August 23 at 8pm. And four minutes earlier on each successive night e.g. 8.56 on August 8.
To use the chart hold it above your head while facing south so that you can look directly from the chart to the sky.
Please note all times given in this article are in GMT so remember to add an hour to get the time in BST.
Sun: Astronomical darkness increases to six hours by the end of the month, so fainter objects are again becoming observable.
Mercury and Venus: Both of these inner planets are closer to the Sun than the Earth so are never very far from the Sun, especially Mercury.
Mercury sets about 25 minutes after the Sun on August 6 and is seen against the background stars of Leo almost due west.
On August 18, Mercury is remarkably close to Mars.
Venus is an evening object throughout the month and can be seen against the background stars of Virgo but exceptionally low in the sky, making it difficult to observe clearly.
The planet sets in the west about 60 minutes after sunset all month.
When Venus is seen so low in the sky it is mistaken for a UFO because of its apparent motion relative to foreground objects, actually caused by the observer’s own motion.
Mars: The red planet is still visible but is fainter than ever as it moves further away from the Earth.
It may be seen against the background constellation of Leo and always close to Mercury.
The best time to spot Mars this month will be on August 18 when it lies exceptionally close to Mercury.
Mars is now significantly fainter than Mercury.
Jupiter: The largest planet rises in the East around 8.40 on August 1 and another two hours earlier by the end of the month and is seen against the background stars of Capricornus.
Jupiter reaches opposition on August 19 and the planet is at its brightest magnitude of -2.9 on this date.
Opposition means that the planet reaches its maximum altitude above the horizon - a little more than the span between your thumb and little finger at arm’s length in this case - and lies due south at midnight, when the Earth is directly between the planet and the Sun, so astronomers are hoping for many opportunities to observe the giant planet.
The coloured bands and zones on the surface of the planet can be distinguished with small telescopes as can the Great Red Spot, a colossal hurricane, greater in diameter than the planet Earth.
The Galilean moons can be seen with a good pair of binoculars or a small (bird-spotting) telescope.
DSLR images of the planet will also pick up the moons.
Watch out for small black dots seen against the surface of Jupiter itself.
The moon Io will cast its shadow onto Jupiter’s banded surface on August 20 and the moons Europa and Ganymede will cast their shadows on August 22 as they pass between us and the giant planet.
Saturn: The ringed planet can also be found against the stars of Capricornus, rising in the East around 20.00 on August 1 and another two hours earlier by August 31.
Saturn also reaches opposition but on August 2 Saturn reaches a similar altitude to that of Jupiter.
The rings are beginning to open out, from our point of view and are consequently becoming brighter.
Saturn’s largest moon, Titan, can be seen above and to the right of the planet with a good pair of binoculars or a small telescope.
Uranus and Neptune: Uranus is visible all night long throughout August and is seen against the background stars of Aries.
At magnitude 5.8 it is visible in binoculars.
Look for a tiny greenish disc compared to the pinpoints which are the stars.
Neptune is seen against the background stars of Aquarius (below the asterism known as the Square of Pegasus).
At magnitude 7.8 it will require large binoculars or a small telescope to find it.
Neptune displays a smaller and truly blue disc compared to that of Uranus.
Meteor shower: The Perseid meteor shower peaks on August 12-13 this month.
This is the best shower of the year with up to 60 meteors an hour including some very bright ones.
Comet: There are no bright comets expected this month.
The Last Quarter Moon occurs on August 1 with New Moon on August 7. First Quarter follows on August 15 with Full Moon on August 22.
Data supplied by Simon Harding, Observations Secretary Torbay Astronomical Society
The next meeting of the Torbay Astronomical Society, complying with the current Covid regulations, will be online via Zoom.
In September, members hope to begin meeting at the Torquay Boys' Grammar School again. Visitors and prospective members especially welcome.
For details, contact the TAS secretary on firstname.lastname@example.org