Saturday, December 9, 2023

Chaos in the heavens


NASA depiction of space debris


Amateur astronomer Brian Watkiss peers into the Village night sky.

June: a month when, to an astronomer, it never really gets dark. But, there are still things to see in the twilight. After 60 years of launching items into space, the heavens above us are starting to get overcrowded. The USA is tracking almost eighteen thousand objects in orbit round the planet, of which only about fifteen hundred are operational satellites.

Last year alone, nearly four hundred objects were launched into space and there are, literally, millions of tiny bits of debris up there too, waiting to cause chaos in the heavens (is that the name of song by a heavy metal band?).

Fortunately, for us stargazers here, a lot of this space hardware can provide a little distraction on a warm (?) summer evening. All that is required is a comfy seat, some pleasant company and, perhaps, a little light refreshment.

As the sky darkens, from about ten o’clock, you will soon start spotting “stars” drifting across the sky, at about the speed of an aeroplane but with no flashing lights. These are satellites and as it gets darker, more and more become visible. It can soon get competitive, with everyone striving to be first to spot the next one (or is that just me?).

The most spectacular of all is, of course, the International Space Station. Its brightness can be quite astonishing and everyone should make an effort to see it. You can find out when it’s due on and, incidentally, identify other objects too.

If you have a really good view of the north-western horizon and it’s really clear, you may get one last glimpse of Mars. A thin crescent Moon is close by on the 5th to give you a clue. Then as the month progresses, Mercury starts to appear, in the same direction but you might need binoculars to pin it down. The two planets make a very close approach on the 18th and Mercury reaches its highest point in the sky on the 23rd.

Over on the opposite side of the sky, in the south east, we start to see Jupiter rising, from about ten thirty onwards. This will be easier to spot as the largest planet is bigger and brighter and is on the other side of the sky to the Sun. In fact, on the 10th it is exactly opposite and is said to be in opposition. It will, however never get very high in the sky at this time of year.

The new Moon in June (!) is on the 3rd, so after this date will appear as a thin crescent, getting thicker and rising earlier each day until the 17th. This is when it is full and this month it is known as a Strawberry Moon. Just as with Jupiter, the Moon never gets very high above the horizon and so always looks much bigger. This is a well-known effect and is called “The Moon Illusion“, so have a look at the rising Moon for yourself and see if you can work out what’s going on.

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