SOMETHING exciting is happening at the end of this month. On the evenings of 30 and 31 May, astronomers around the world will be watching the skies to see whether a new meteor shower, which has been predicted for almost 100 years, comes to pass.
In May 1930, a comet called 73P/ Schwassmann-Wachmann 3, also known as SW3, was first spotted by German astronomers. Shortly after its discovery, there were predictions that it would cause a meteor shower if it travelled close enough to Earth.
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SW3 is a short period comet that passes the sun every 5.4 years, but it wasn’t spotted again until 1979. This is because it was so faint, nobody had noticed its orbit veering off course due to the gravity of Jupiter. In any case, the comet still hadn’t fragmented enough by 1979 to produce debris that would burn up in Earth’s atmosphere, which is necessary to create a meteor shower.
Then, in 1995, astronomers watched as SW3 started to break apart into four large fragments. By 2006, they could see a total of  littering SW3’s trail with debris. In 2011, however, the comet stayed behind the sun in relation to Earth, meaning it wasn’t easy to observe.
Now, the comet is approaching perihelion – the closest point to the sun in its elliptical orbit – so we are in a good position to see both the comet and its associated meteor shower, if there is one to be seen. Luckily, Earth is also making a much more direct path through SW3’s trail of debris this year, which should help.
have predicted that, if there is to be a meteor shower, it will peak on 31 May. Some astronomers are also optimistic that, despite the low density of SW3’s trail, the dust released by the break-up of the comet will be enough to produce a visible meteor shower. They also believe it will be best viewed from North and Central America.
The meteor shower associated with comet SW3 is called the Tau Herculids. Usually, meteor showers are named after the point in the sky from which they radiate, where most of the meteors appear to “start” from. Thanks to Jupiter moving the comet out of its original orbit, the shower is predicted to start not from Hercules, but from the nearby constellation Bootes. Bootes is recognised by finding its bright star, Arcturus, which is part of a pattern of stars, or asterism, called the Summer Triangle. Another way to find Arcturus is to find the Plough, or Big Dipper, in the constellation Ursa Major, then follow the arc of the handle of the dipper, until you see a bright star.
The good news is that there will be a new moon the day before the shower’s predicted peak, giving us the best chance to see the meteor shower. Even if you don’t catch it, you can try to spot the comet itself up until the end of August, if you have a telescope.
What you need
A bit of luck
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