Greetings stargazers.
There is a dragon in our night sky. Draco is one of the circumpolar constellations that is above the northern horizon year-round, but is especially well-positioned to pick out at this time of year.
On late summer evenings Draco is above Polaris, so is much higher in the sky than it will be six months from now. It has only three stars that are brighter than magnitude 3, so this constellation would be hard to see in a light-polluted area. However, with our nice, dark, Four Corners skies, it is straightforward to follow the dim line of stars snaking around the Little Dipper. The star pattern is very snakelike, and I have never seen wings on any mythological drawings of this particular dragon.
There are several ways to identify the stars of Draco, but the way I have always done it is to start with the line of dim stars between the Big and Little Dippers. The tip of the dragon’s tail is about halfway along the line from Duhbe and Merak, the pointer stars of the Big Dipper, to Polaris, the North star. From the tip of the tail, the line of stars goes right between the Big and Little Dipper, and then wraps around the Little Dipper before doubling back to complete a large, backward “S.”
The head of Draco is a grouping of four stars in the direction of Vega. Vega is the very bright star that is now near our zenith, the point straight overhead. Also near Draco’s head is the foot of the constellation Hercules. One story says that Hercules, during one of his 12 labors, had to kill the dragon in order to steal the golden apples of Hesperides. This would explain the foot as a conquering display, rather than a hiking misstep.
The third star from the tip of the tail is Thuban. Its significance is that it was the pole star while the Great Pyramids were being built. The Earth’s axis wobbles like a spinning top, taking about 26,000 for a single turn. During that cycle the Earth’s axis will point to several different stars which get to take their turn being the pole star. In another 12,000 Vega will take its turn.
There are several deep sky objects in Draco that can be seen with 8 to 10 inch telescopes. The Draco triplet of galaxies show a face-on spiral, an edge-on spiral, and an elliptical galaxy, making a nice, contrasting set. The Cat’s Eye nebula is a good example of a planetary nebula. It is fairly bright, but unfortunately too small to get much detail through an eyepiece.
This month:
Besides dragons, this is a great time of the year to see the birds of Cygnus and Aquila, now high overhead as part of the summer triangle. Vega, the brightest star in the sky right now, and almost straight overhead, is one of the three triangle stars. Deneb, to the east, is the tail of Cygnus the swan, flying south along the Milky Way. Altair, the southernmost star of the triangle, is the brightest star in the constellation Aquila, the eagle, that is flying north along the Milky Way.
The planets Jupiter and Saturn are in great positions to see during the evening for the next few months. Saturn was at opposition on Sept. 27, and is prominent in the southeastern sky after sunset. Jupiter crosses the eastern horizon a bit after 10 p.m. If you look at Saturn with binoculars, you might be able to see an elongated football shape, rather than a tiny disk. Jupiter through binoculars should show the four Galilean moons.
On the morning of Oct. 14 is the annular solar eclipse. The moon will pass in front of the sun, but it will be near the apogee of its orbit, so a bit farther away from us than its average distance. That means it can’t completely cover the sun and we will be left with a ring of fire around the edge. Although the complete ring of fire will be visible at nearby places such as Mesa Verde, Farmington and the Old Fort Lewis, Durango is unfortunately a few miles away from this total ring.
Useful links:
Draco
https://en.wikipedia.org/wiki/Draco_(constellation)
Draco Triplet
https://apod.nasa.gov/apod/ap230701.html
Astronomy picture of the day
http://apod.nasa.gov/apod/
An Astronomer’s forecast for Durango
http://www.cleardarksky.com/c/DrngoCOkey.html?1
Old Fort Lewis Observatory
http://www.fortlewis.edu/observatory
hakes_c@fortlewis.edu
Charles Hakes teaches in the physics and engineering department at Fort Lewis College and is the director of the Fort Lewis Observatory.
