By CLIVE JACKSON
WELCOME TO the October night sky. This is the month when we really notice the nights lengthening and the constellations of summer are replaced by those of the autumn. The Milky Way is now low in the west in the late evening and, overhead, we now have the constellations of Pegasus and Andromeda.
At this time of the year, we can see beyond our own Milky Way galaxy and out into the depths of the universe and to the many galaxies that lie beyond. Most of these objects are hundreds of millions of light years away and are difficult to see, even with a large telescope, but there is an exception to this. In the constellation of Andromeda, we can see the closest big galaxy to us, as it is only two-and-a-half million light years away.
This is truly a giant galaxy and is twice the size of our own, having around 400 billion stars. This galaxy is just visible without any optical aid as a faint smudge to the south of the Milky Way.
The gravity of this galaxy is so strong, that it is attracted to our own and we will both merge together in the far distant future. This is, in fact, a good thing, and it is a natural process of galactic evolution, but we will have to wait ten thousand million years to see it happen!
The planet Jupiter has now disappeared from view in the west after sunset, and so we now have no bright planets visible in the evening. We shall have to wait until winter for Saturn to rise in the east before midnight.
The Moon is Full on October 7, Last Quarter on October 14, New on October 22 and First Quarter on October 29.
Clive Jackson is the director of the Astronomical Observatory of Tavira (Sitio do Malhão) and the Camera Obscura (next to the Castle in Tavira), specialising in education and public outreach. Tel 281 321 754, Fax 281 324 688, e-mail: email@example.com or visit http://www.cdepa.pt