Here’s a close-up look at the constellation Auriga the Charioteer. Its brightest star is called Capella.
This constellation and its brightest star are easy to identify in the northeast by mid to late evening. If you don’t see them, try looking a bit later at night — especially if you live in the southern U.S. If you’re unsure whether you’ve identified Capella, you can always look nearby for a small triangle of stars. Capella is sometimes called the Goat Star, and this little triangle is known as The Kids.
Auriga carrying the goat and kids depicted in Urania's Mirror, a set of constellation cards published in London c.1825. Via Wikipedia
Capella is located at one corner of the constellation Auriga. Capella marks the Charioteer’s left shoulder. Menkalinan, the second-brightest star in Auriga, marks the right shoulder. Also, notice the star Elnath at the southern tip of Auriga. This star used to belong both to Auriga, where it was known as the heel of the Charioteer, and to the constellation Taurus, where it represented the tip of the Bull’s northern horn. In the last century, though, the International Astronomical Union decreed that this star shall belong only to Taurus!
In a dark sky, using binoculars, you can spot some easy-to-see star clusters within Auriga: M36, M37 and M38. That’s at mid-evening in the northern states and later evening in the southern states: The beautiful star Capella and its constellation Auriga the Charioteer.
Here’s something I don’t understand: Today in the morning, right before sunrise, Arcturus appeared above the son (rises before it, just a few degrees above), then at sunset, it sets AFTER the sun, and it is located some 15 degrees above the horizon, so it is viewable for almost an hour and a half after sunset… How can a star rise a few minutes before the sun and then set after it, almost hour and a half later the same day? It blows my mind! I suppose it has to do with the ecliptic and how wide the angle of each object’s transit around the sky dome is… Now the weird thing is that Saturn for example, rises a bit earlier than the Sun as well as Arcturus, but it sets also a bit earlier than sunset, as it should be, unlike Arcturus, but Saturn is much closer in declination to the Sun…
Bibi,
Great observation!
Here’s how it works. In the Northern Hemisphere, the farther north the sun (or star) resides from the celestial equator, the earlier that it rises and the later that it sets. The converse is also true: the farther south the sun (or star) resides from the celestial equator, the later that it rises and the sooner that it sets. That’s why the sun is out for the longest period of time on the summer solstice, and the shortest amount of time on the winter solstice.
In late October, the sun and Arcturus cross the meridian together at solar noon. But Arcturus is at declination of over 19 degrees north of the celestial equator (same as the sun’s declination in late July) while the late October sun is at a declination of 13 to 14 degrees south. That’s why Arcturus sets after the sun but rises before sunrise at northerly latitudes at this time of the year.
Read the upcoming Halloween feature Arcturus is a ghost of the summer sun at http://earthsky.org/tonight/arcturus-ghost-of-the-summer-sun
Bruce
Bruce,
Nice explanation, thanks! Now I know why Sirius rises about an hour earlier than Canopus in my sky, even though Canopus is located a tad bit more to the west (right ascension), so if they were similar in declination, Canopus would be “up” 1st…
And I imagine exactly the opposite happens in the southern horizon, say somebody located 20 degrees latitude, same as me but south of the equator, would see Canopus rise much earlier than Sirius… Fascinating stuff! :)
Yes, you got it!
I wonder when it will be the next time Jupiter will do as Arcturus does every year –be in a similar right ascension but considerably farther north from the Sun in declination, so we people in the Northern Hemisphere can see it rise and set before and after the Sun, during the same day– that would be very interesting to see!
Bibi,
When the sun and Jupiter are in conjunction (north and south of one another), there is never much difference in the declination between the sun and Jupiter. Jupiter never strays far from the ecliptic.
Arcturus, on the other hand, lies about 33 degrees north of the ecliptic. So even at conjunction in late October, the sun and Arcturus are a whopping 33 degrees apart from one another.
Every 8 years, at a particularly favorable Venus/sun conjunction, Venus swings as far as 8 degrees north of the sun. (This last happened on March 27, 2009, and will happen again on March 25, 2017.) At these times, Venus appears in the east as a morning star and the west as an evening star on the same day. I’ve seen it!
Bruce
OMG what a cool event, Bruce! I’ll bet you were one of the very few people who knew that day that they were seeing the same “star” (Venus) rise and set without the presence of Sun, the very same day… Too bad I’ll have to wait until 2017 to be able to see that myself –and pray for a clear sky as well, at both sunrise and sunset lol–