Autumn is under way in the Northern Hemisphere, and if you are an avid sky gazer you just might have noticed signs of the season’s change.
Many of the striking star groups and our beautiful Milky Way galaxy, which made for great stargazing on balmy summer evenings, are still visible in the western sky. But the appearance now of the brilliant star Capella ascending above the northeast horizon in the evening hours is a promise of the chillier nights to come. And indeed, in just another few weeks the constellation Orion and his neighbors will be dominating the evening skies, reminding us of the approaching winter season.
Still very well-placed in the night sky is the “Summer Triangle,” a roughly isosceles figure composed of three first-magnitude stars, Vega, Altair and Deneb. Many have asked me over the years why it is called it the “summer” triangle since it’s nearly overhead during the late-evening hours as summer transitions into fall. But during the summer months the Triangle is visible all night from dusk to dawn, whereas during autumn, as the evenings grow colder, this configuration sinks lower and lower in the west.
Watery stars in the sky
During the mid and late-evening hours, the stars of the autumn season cover much of the eastern and southern parts of the night sky. In fact, this whole area has been called the “Celestial Sea,” because many of the constellations have an association with water.
For example, looking toward the south-southeast is one member of this watery fraternity; the only one whose name is attached to a popular song: “Aquarius.” And yet how many who have heard the song know what the constellation Aquarius really is. This zodiacal star pattern traditionally represents a man holding a water jar (marked by an inverted Y-shaped group of four stars), which is spilling a vaguely marked stream of water southward into the mouth of another constellation: Piscis Austrinus, the Southern Fish.
Across southern Canada, the northern United States and much of Europe, the stars that make up Piscis Austrinus usually cannot be seen. Although above the horizon, they are too low to penetrate the horizon haze. At more southerly latitudes these stars are much higher up in the sky, though still quite dim.
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SOURCE: Discovery News
Joe Rao, SPACE.com