Where have all the bright stars gone?
Wednesday, March 9, 2016
Okay, first off, you need to be out at your favorite dark-sky spot at least an hour after local sunset--a little later would be alright too--looking southeast.
One of the first questions we might ask is, "Where have all the bright stars gone?" And, it would be a good question.
We have been accustomed to looking at all the bright stars of Orion, Taurus, and Gemini but looking to the southeast now all we have left is Castor and Pollux of Gemini. However, if we look slightly right across the meridian--the imaginary line that divides the west from the east half of the sky--we will see that Orion and friends have simply moved over there.
Also, something else has happened. When looking at Orion and company, we were looking at the Orion Spur, a part of one of the spiral arms of our galaxy. Looking southeast now we are looking out into empty (almost) space where there are no bright stars, or at least a very few.
What we are looking at is a relatively dim constellation, Cancer, the Crab, which has no stars brighter than third magnitude. Now, true, Castor and Pollux are still above to our right, but they hardly make up for what we have lost.
Leo is there too, just rising over the horizon with his distinctive backward question mark for a head and mane and a triangle of stars for his hindquarters. Most of his stars are also also no brighter than third magnitude, except for the dot at the end of the question mark. That is first magnitude Regulus.
But, there is an extra bright object just below the hindquarters of Leo, that is the planet Jupiter, which reached opposition yesterday, Tuesday, March 8.
Opposition means it is opposite the Sun in the sky and is at its biggest and brightest for the year. Jupiter will also make a super telescopic sight for those so inclined. It will rise at sunset and set at sunrise and be visible at some place in the sky until September.
Now, what about that "Crab Monster" I mentioned last week? That, of course, would be the constellation Cancer, The Crab, or at least that what it has been called since ancient astronomers named it so on their maps.
Since we are outside looking southeast above and right of Leo, and below and left of Castor and Pollux we will find the dim stars of Cancer. The ancients may have seen a crab, I see the upside down "Y" of the peace symbol from the '60's.
Of the several things of interest about Cancer, one is that the point of the summer solstice was located there in 150 BC, but due to the wobble of Earth's axis--called the precession of the equinox--that point is now located between Gemini and Taurus.
Another interesting point is the ecliptic--the path the Sun and planets seem to follow throughout the year--runs right through the middle of Cancer. That is why we often see the moon and planets wandering past it.
But one of the most interesting points, at least for me, is Cancer is the location of the beautiful M44 star cluster, also called "The Beehive." If you look at it with binoculars it does look like a bunch of swarming bees.
SKY WATCH: New moon yesterday, look for a thin crescent in the west in a couple of days. Daylight Saving Time starts Sunday, March 13, so don't forget to "spring ahead" on Saturday night. Also on March 13th, British astronomer William Herschel discovered the planet Uranus in 1871.
NEXT WEEK: Spring is about to sprung and more astronomical blathering.