Useful links
Galileo’s Telescope
https://catalogue.museogalileo.it/object/GalileosTelescope_n01.html
Aurora forecast
https://www.swpc.noaa.gov/products/aurora-30-minute-forecast
Astronomy picture of the day
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
Greetings, stargazers.
I recently traveled with the Durango Choral Society to Florence, Italy, on a trip originally scheduled for 2020. Among the many more famous attractions, I toured the Galileo Museum. Formerly known as the History of Science Museum, the name Galileo was added to attract more visitors. Although Galileo didn’t invent the telescope, he was the first person to use one to look at celestial objects, and several of his original instruments are on display in the museum. Perhaps because he was its most famous user, the kind of telescope having one lens with a positive focal length and one with a negative focal length is called a Galilean refractor telescope. These are not common in the twenty first century because they have severe limitations with their field of view, light gathering ability, and magnification.
June is the month with the fewest truly dark hours for stargazing but does offer some very rewarding constellations, asterisms, and star fields. An asterism is simply an easily recognizable pattern of stars that may or may not correspond to a constellation.
The Big Dipper asterism, which is part of the constellation Ursa Major, is high overhead this month. Dubhe, and Merak, the two stars at the end of the dipper, point to Polaris to help you find north in case your smartphone compass mysteriously stops working. At the other end of the dipper, the handle “arcs to Arcturus.” Arcturus is the very bright star high in the southwestern sky.
Vega is about the same brightness as Arcturus and is seen to the east. Now that Jupiter is moving behind the sun, Venus is the morning star, and Mars is getting farther away, the bright stars Arcturus and Vega have a chance to outshine the planets during your evening stargazing experience.
The summer triangle is an asterism that first appears in the eastern evening sky at the beginning of summer. It comprises three very bright stars that are in three different constellations. The stars are Vega, in the constellation Lyra, Deneb in the constellation Cygnus, and Altair in the constellation Aquila.
Vega is the brightest star in the small constellation Lyra. In Lyra, the Ring Nebula, M57, and Epsilon Lyrae, the “double,” are easy to find with a telescope, but require high magnification to see any detail.
The second star in the summer triangle is Deneb, which is twenty-three degrees, or a little over two fist widths, to the northeast of Vega, and therefore closer to the horizon at dusk. The name Deneb is derived from the Arabic dhaneb, meaning tail, and Deneb is the tail of Cygnus the swan. The body and long neck of the swan follow the Milky Way toward the south to Alberio, the star making the head of the swan.
Alberio is near the center of the summer triangle and is one of the prettiest double stars in the sky. This double star is one of the easiest to resolve in a telescope with low magnification. The brighter companion is yellow and makes a sharp contrast to the dimmer, blue companion. Besides a swan, Cygnus can be seen as the Northern Cross, with Deneb as the head of the cross and Alberio the foot.
Because it is aligned with the Milky Way, the background of Cygnus is rich in dim stars when viewed with binoculars, and several open clusters can be seen. On very dark nights the bright patch of Milky Way that makes the North American nebula is visible just to the east of Deneb, but the shape of North America won’t show up except in photographs. The Veil nebula is a portion of a supernova remnant and can be seen on dark nights along the eastern wing of the swan with large binoculars or wide-field telescopes.
The third star in the summer triangle is Altair, a bit over thirty degrees to the south of Vega. Altair is the brightest star in the constellation Aquila, the eagle, which is flying north along the Milky Way. Because it is also along the Milky Way, there are lots of stars and clusters to see as you scan the region with binoculars. Near the tail of the eagle, but just outside the boundaries of Aquila, is M11, the Wild Duck cluster, one of my favorites.
I understand there was another chance for aurora to be visible from Durango last weekend. Even though I had clear skies, the sky from the middle of Florence didn’t allow viewing.
Charles Hakes teaches in the physics and engineering department at Fort Lewis College and is the director of the Fort Lewis Observatory.
