This week, I was going to write about the asteroid belt, and the diversity of the many objects and bodies found in that mysterious region of space between Mars and Jupiter. But the asteroid belt will always be there. Suddenly, we were presented with an opportunity to view something so fleeting, and so rare.
Instead, we will focus our attention far beyond the reaches of our solar system this week, to a distant pair of stars that have always been so remote, and so small, that they have never been visible from earth. Until now.
They are in a region of the sky in the constellation Sagittarius, just below the lid of the teapot. “The Teapot” is an asterism within the constellation of Sagittarius. An asterism is a grouping of stars that resemble an object, or form an image of something that is familiar to us. The most famous asterism is The Big Dipper. Most think The Big Dipper is a constellation, but that supposition is incorrect. It is an asterism that lies within the constellation of The Great Bear, up near the north star. The handle of The Dipper is the tail of The Bear. Likewise, The Teapot is the body and outstretched arm of Sagittarius.
Right now, the distant stars below the lid are increasing in brightness, becoming visible from earth for the first time. The increase in brightness is due to a massive thermonuclear explosion on the surface of one of the stars. The resulting explosion is called a nova.
The nova is now visible with the naked eye, and scientists think it will continue to increase in brightness for some time. A nova is produced in binary star systems. A binary star is a pair of stars that revolve around each other. The smaller, dwarf star, begins to strip gases away from the larger companion star. These gases build up on the hot surface of the smaller star, until the buildup results in a nuclear explosion, which casts debris off into space, and increases the brightness of the star, until that star, previously so small and so distant, suddenly becomes visible from earth for the first time. The nova was only discovered last week, as the light from the explosion became apparent from earth. At that time, the explosion was expanding from the star at a rate of 6.2 million miles an hour! Before long, the explosion became visible to the naked eye.
Sagittarius lies within a region of space with which we have all become familiar as of late. It is just to the left, or east, of Scorpius. Three weeks ago, we focused on Saturn, which is in the upper part of Scorpius. Go outside this week, just after 5:00 a.m. Look in the southern sky for Saturn. Just below the bright planet is the brightest star in the arc of Scorpius, Antares. A little lower, and to the east, is The Teapot. It takes only a little imagination to pick out the form among the dimmer stars. It sits upright on the south-east horizon, The Milky Way forming the steam from the spout. Within the body of The Teapot, just below the lid, you will see a star, fainter than the others that form the pot. But if you watch it, over the course of days, it will increase in brightness. Then later, as the explosion dissipates in space, it will become red as the light from the explosion is disbursed. It is a star that has always been there, but has never been seen from earth, and in just a few weeks, it will once again fade into oblivion, as the distant sun fades back to its former magnitude.
Though scientists have not confirmed the distance to the star, it is thought to be at least thousands of light years away. So, the explosion you are witnessing today, as you look at the nova in The Teapot, actually occurred thousands of years ago. So distant are the stars were talking about, that it has taken the light from the explosion all those millennia to cross the intervening space, until we are finally seeing the result of the explosion now. Chances are, it exploded long before the time of Moses and The Pharaohs Of Egypt. In ancient times, a nova was seen as a terrible omen, a predictor and precursor of doom, as it was thought a new star was coming into the sky. We now know it is simply the brightening of a distant star that has been there all along.
Venus is ever growing nearer as it catches us in its orbit. Weekly, we are keeping track of its progress, as the distance to our sister planet decreases. Last week, it was 119.04 million miles distant. This week, the distance has decreased to 115.32 million miles. It has grown nearer in the past week by nearly 4 million miles!
Thanks for your interest in astronomy and our featured articles! If you have any article requests or questions, contact Spanish Peaks Amateur Cosmos Enthusiasts [SPACE] at firstname.lastname@example.org for inquiries about scientific information.
William J. Bechaver is the Director of SPACE – Spanish Peaks Amateur Cosmos Enthusiasts [SPACE], the local Astronomical Society in Southern Colorado.