A look at the October night sky

Jupiter also continues to dominate the south in the early evening. Use binoculars to watch its four main moons changing position from night to night. With a copy of either Sky and Telescope or Astronomy magazine, and a little work, you should be able to identify each of the moons.

Our challenge for this month is to locate the asteroid Vesta. It is the second-largest, and brightest, of the asteroids. It will reach opposition on Oct. 28 in the constellation Cetus. Get a star map and use your binoculars to locate it. From its 1807 discovery until 1845, it was classified as a planet. Currently it is classified as an asteroid; however, it may be upgraded to a dwarf planet after NASA's Dawn probe visit in 2011.

With autumn's arrival, the constellation Cygnus the Swan moves into the western sky and tilts more toward the south, indicating the time of migration of many birds to warmer latitudes. You can find it almost directly overhead early in the evening. You can quickly recognize its tail star, Deneb, as the easternmost member of the Summer Triangle. The swan's neck extends to the southwest. Very near the central star of the neck is Cygnus X-1, a strong source of X-rays and now accepted as a black hole. Albireo, the star representing the swan's head, is an orange and blue binary that can be viewed through binoculars or a small telescope.

— Rodney Ash, Special to The Seattle Times

Rodney Ash is a member of Seattle Astronomical Society, www.seattleastro.org. Star Watch appears in NWWeekend the first Thursday of each month.