Thursday, March 28, 2024

The parallax view

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Amateur astronomer Brian Watkiss peers into the Village night sky.

May, and it’s nearly ten thirty before the sky is dark enough to see anything. A massive change from December when you had to put the lights on just after lunchtime! However, Venus is visible all month, as soon as the Sun goes down, just to the north of west.

It will be very bright, very low and the subject of nearly every question I will be asked for the next few weeks. Look for it on the 16th with a very thin crescent Moon just to the left.

Mars is still with us, not as high now, in the south west as soon as it gets dark and still very obvious by its almost pink hue.

Now, I’d like to talk parallax for a moment. This is the phenomenon whereby as you walk past a lamp post, the scenery behind the post moves, giving the post an apparent motion relative to the background. This is exactly what has happened with Mars.

During March, as the Earth passed by, Mars appeared to move closer to the stars Castor and Pollux. Now, however, Earth is further round its orbit and moving more or less directly away from Mars, so we will see its true movement and during the month it will move closer to Leo. Watch it day by day.

Look to the left of Mars and you should soon spot the reversed question mark that is the head of Leo. Further left and lower is Saturn, noticeably brighter than any of the stars of Leo.

Now, I’d like to show you something very few people have seen (but only because they haven’t looked). If you look high overhead, you will see the familiar shape of the Plough, looking like a saucepan, with its handle out to the left, pointing slightly downwards.

The two stars forming the right hand side of the pan, act as pointers to the Pole Star or Polaris. If you trace a line upwards, away from the base of the pan, you will come to this unremarkable star (if you haven’t fallen over!), which remains fixed in the sky in the north. The Plough is part of a larger constellation called Ursa Major or the Great Bear. For this reason, the Plough is called an Asterism.

If you imagine that the handle is the bear’s tail, you will soon see the rest of the stars to the right of and below the Plough, forming what makes a passable shape of an animal (I think it looks more like a pussy cat), with the head consisting of a pattern of stars very similar to Leo’s.

The Plough is merely the brightest of the stars in this constellation but when it is high overhead, as it is now, and away from the full Moon, it is easy to see the rest of it – but how many people have looked?

May should see the final launch of the Space Shuttle Atlantis on the 14th, although this might change. There are only two more Shuttle flights after this one, so I, for one, will be keeping an eye on heavens-above.com hoping to spot it as it approaches the International Space Station.

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