The Sky This Week, October 10-16
“The Sky This Week” appears every Tuesday. It is written by Ian Clarke, Director of the Hatter Planetarium at Gettysburg College. The planetarium offers regular educational presentations about the stars and the skies; there’s something for early elementary through adults. We are accepting field trip requests for the 23-24 academic year. Fall schedule of public shows is available here! Illustration created with Stellarium.
Eclipse types image: Image credits (left to right): Hinode/XRT, NASA/Aubrey Gemignani, NASA/Noah Moran
On October 14, an annular eclipse of the sun will sweep a path across part of the western US. An annular eclipse, sometimes known as a “ring of fire” eclipse, occurs when the geometry of the sun, earth, and moon line up for a solar eclipse when the moon is near the far point of its slightly elliptical orbit. By coincidence, the sun and earth appear about the same size in our sky. Although the sun is about 400 times larger than the moon in diameter, the moon is 400 times closer. The apparent size match is near enough that when the moon is near its apogee (far point in its orbit), its apparent size is not quite big enough to cover up the sun, leaving a ring of the sun’s disk visible. The beautiful corona is not visible in an annular eclipse because it can only be seen from Earth when the sun is completely blocked.
Areas not in the path of the annular eclipse will see a partial eclipse, and the farther you are from the path, the less of the sun will be covered. Here in the Gettysburg area, 28.8% of the sun will be blocked by the moon. This will not be enough to notice in the environment, and of course, you should never look at the sun without approved protection. Eclipse glasses (not regular sunglasses!) or a pinhole projector can both be safe means of viewing. Read more about safety here. The partial eclipse will begin locally at 12:00 noon EDT and will be at its peak at 1:18 p.m. The sun will be completely uncovered again at 2:37 p.m. You can read much more about the eclipse here and here.
Ian Clarke is the director of the Hatter Planetarium at Gettysburg College. In addition he has taught introductory astronomy labs and first-year writing there for over 30 years (not necessarily all at the same time). He was educated at Biglerville High School, the University of Virginia, and the University of Iowa. He lives in Gettysburg.