Size is a relative thing. To a flea, an ant is big. To an ant, we are big. To us, an elephant is big.
The largest thing we normally have any interaction with is the Earth. Although we cannot see it directly, spending six or more hours in a cramped seat on a flight to Europe gives us some idea of the size.
If you’ve been paying attention, you’ll know the two bright lights in the south east after dark are Mars and Saturn; the first a little smaller than the Earth, and Saturn quite a bit larger. But, the winner in size of things we can see, is the Sun, with a radius 109 times that of our planet.
Speaking of Mars and Saturn, 6 degrees (3-4 fingers) below and a little right of Saturn lies the red star Antares, about the same brightness as Saturn but red like Mars.
Translating into ‘Heart of the Scorpion’, Antares is a supergiant star lying at the heart of the constellation Scorpius.
The 16th brightest star in the sky, it can be seen low in the south from late March through August. Near its brightest now, it is known to vary unpredictably in brightness.
Antares is old, as stars go. It was quite average in its youth, but like many of us over the years, it’s put on a little extra weight around the middle. One of these days, could be tomorrow, could be in a few million years, it will run out of material to burn, and will explode in a massive supernova and collapse. Luckily, the star is 640 light years away, so its effect on us would only be a really good light show (in fact, it could have already happened; at that distance, light from the event would take six and a half centuries to get here).
The story would be much different if Antares existed where the Sun does, because compared to the Sun, Antares is big. If Antares lay at our Sun’s position, its surface would extend past the first four planets of our solar system, out to a distance a little beyond Mars. Exactly when it exploded would be irrelevant, because we would not be here; any planets that once existed in the vicinity of Antares would have been incinerated millions of years ago.
From a country sky, if you have good eyesight (or binoculars) and look a finger width to the right of Antares, you would see a fuzzy patch classified as a globular cluster and commonly referred to as Messier 4. Compared to M4, Antares is a flea (and a story best left for another article).
To us, Antares is so big we can not even properly picture it, and M4 so unusual, you have to see it in a telescope to believe it. ‘Tis a wondrous master plan that makes such an interesting universe accessible from your own back yard, should you only choose to look.
