Heacham and Hunstanton at Night

Heacham and Hunstanton at Night
Hubble space telescope image of Jupiter. NASA

Your guide to the night sky during August

The Perseids meteor shower is what I always write about in August. Like almost all things in astronomy, what goes around, comes around.

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A Perseid fireball against a faint Milky Way. Internet

The Perseids peak on the night of the 12th, morning of the 13th. I anticipate a clear sky because Full Moon is also on the 12th and it will be another supermoon so a tad brighter than usual. Consequently, most meteor trails will be washed out. If there is patchy cloud that obscures the Moon then sightings will be better.

The Perseids shower does strike the Earth’s atmosphere between the 17th July and 24th August so any meteor trails you see in the sky over, essentially, the school holidays will likely be a Perseid.

I say ‘likely’ because there are always random meteors. They are mainly particles of dust orbiting the Sun and if their orbit gets perturbed by something of greater mass they may enter the Earth’s gravity well, fall towards the Earth and burn up.

Space dust and rocks are potential hazards to space craft though there is a lot of space and the chances of a craft being struck are considered remote. Having said that, the International Space Station is continuously being eroded by very fine dust and the James Webb space telescope was struck by a larger particle than the ‘insurance’ anticipated.

Today, some meteor trails will be caused by debris from the ever-increasing numbers of human made satellites. The race is on to become the space highway sweeper and the UK is trialling some ways to capture dead satellites.

Anyway, what else to see? August is a good time to scan the Milky Way with binoculars. There is nothing dramatic about it from our location as the sky is light polluted. However, you can see it as a faint wash of light, high in the sky, running from the NE to the SW.

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Milky Way, Dorset. Internet

Our Galaxy is a spiral, fatter in the middle than at the edges and our Solar System sits about a third of the way in from the centre.

When you look at that band of light you are looking into the galaxy. The milky wash is the overlapping light of billions of stars. A clear, dark, sky will enable you to see great rifts in the light areas. These are huge areas of dust and gas which hide the stars behind them. Infra-red and radio telescopes can penetrate this darkness.

The SW end forms the background of the constellation of Sagittarius. This is the direction in which the centre of the galaxy lies. Far more stars will be found there. The distance to the centre is almost 27 000 light years away. (1 light year is the distance light travels in a year; it covers 186,000 miles or 300 million metres in a second. I will let you work it out).

The Milky Way is about 100,000 light years across and 1000 light years thick with the fatter centre 10 times that.

At the centre of the galaxy is a supermassive black hole. It has the mass of about four million of our Sun’s. Its gravity stops light from leaving it hence ‘black hole’ but radiation spills from its edges as matter is ‘devoured’.

Most normal galaxies appear to have a black hole at their hearts. The gravity of such bodies keeps galaxies together and the motion of stars around that centre stops them from all falling inward. This is just the same as our Solar System, the Sun pulls at all the planets but their motion keeps them in orbit. And, just like Mercury being closer to the Sun, has to orbit faster than any other planet, stars nearer the centre of the galaxy orbit the black hole faster than we do.

Near the centre, stars might attain a velocity of 18 million km/hour. The Sun is dawdling at 800,000 km/hr.

(Just for fun, watch tv for an hour. In that time, you will have moved 666 miles due to the Earth’s rotation, 67,000 miles further around the Sun, 500,000 miles about the galactic centre, and 1.3 million miles through intergalactic space due to the motion of the entire Milky Way. Did you notice?)

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James Webb telescope deep field image. NASA

Last month saw the release of the first pictures taken by the James Webb telescope. I must admit I wasn’t too amazed by the deep field picture showing thousands of galaxies. The Hubble space telescope did a similar job in 2004. The James Webb looks a lot further and is, scientifically, more important, it just doesn’t have the same impact. Hubble showed there are countless galaxies out there, James Webb shows countless plus. It also shows arcs of light which are galaxies behind the galaxies in front. The gravity from those bends the light from those behind so they become visible albeit as a distorted image. This is called gravitational lensing.

The James Webb deep field image shows light which was emitted from just after the universe, as we perceive it, began, 13 billion or so years ago. I find some difficulty with this view. The light has taken 13 billion years to reach us so we see those objects as they were all that time ago. So, what is beyond them and what was present where we are now? And, as space looks pretty similar in all directions, why aren’t we at the centre, because we aren’t. Do you see my problem? I start pondering these things when meetings get too much. Answers welcome.

Back to Earth or, at least, to the Solar System.

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Hubble space telescope image of Jupiter. NASA

Saturn and Jupiter are back in the night sky. In the middle of the month, Saturn rises around in the SE around 8pm. By 11pm it is reasonably high, say 30 degrees above the horizon, in the SSE. It is then visible through to dawn, moving towards the west (remember, it isn’t, the Earth is turning east).

From the 15th, Jupiter rises about 10pm in the east. It chases Saturn along the ecliptic and will be reasonably high and higher than Saturn by midnight.

As the month progresses, so both planets rise earlier and attain a greater elevation earlier. They also shift west so, by the end of the month, Saturn is due south at midnight whilst Jupiter is due SE and better placed for observation as it is higher in the sky.

Those of you new to the game of trying to spot planets I write about; Jupiter will be the brightest object in the direction given. It will not have the appearance of a star. Saturn is much dimmer with a yellowish cast but once you spot it, it becomes easier to recognise again

If you have decent binoculars, a spotting scope or telescope, turn them towards the planets. What you are trying to see are four sparks close to Jupiter which are the Galilean Moons and bands of colour on the planet itself.

Hubble’s Latest Portrait of Saturn

Hubble image of Saturn. NASA

Saturn is the ringed planet and you want to see the rings. A good spotting ‘scope or a small astronomical ‘scope will let you. I may offer a viewing around November though it will be weather dependent.

Saturn will be a little dimmer then as it is nearest to us (1325 million km), at opposition, on the 14th of this month. However, the nights are darker in November and both planets will be able to be seen from 7pm.

I used to write descriptions of the planets and their moons and perhaps I will again as the nights get darker. For now, just find the two gas giants and try to see as many details as pm. you can.

Neptune and Uranus are both up late evening but you need to have telescopes to spot them. However, if 2am in the morning is good for you, look about due east, take your eye up from the horizon and find a red dot. This will be Mars. Due south at the same time is Saturn and both planets are at about the same elevation. Between the two, higher and much brighter is Jupiter. On the 1st, Mars is very close to Uranus and, knowing where to look, you might find it as a faint blueish, ghostly dot. So, four planets to ogle if you stay up into the early hours.

You will be so overcome by the wonder of it all that you might not bother going to bed because at 4am Venus rises in the east and it will be brilliant. At 5am on the 26th, in the ENE, you should be able to catch Venus close to a sickle Moon with the Pleiades above them.

So, ponder the eternal infinite, try and work out how far you have travelled in a week, catch a falling star, and look at the neighbours (planetary suggested).

The hedgehogs just want food and water, plenty of water.

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Internet - but the ones who visit me do the same from a plant saucer.


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