Categories: Sky Reports
THE event this week is the total eclipse of the moon on the night of Sunday, May 15. For us in the western half of the country the eclipse is already underway when the moon rises in the east-southeast, just as the sun sets in the west-northwest. (People in the eastern half of the country will see the entire eclipse and the moon will be higher in their sky.) When the moon rises, the moon’s lower left edge is very slightly darker than the rest, but in reality you won’t notice this because the sky is still so bright. At 8:28 p.m. MDT, when the moon is barely above the horizon, the moon begins to move into the umbra, the dark inner part of the earth’s shadow, and from then you’ll notice the moon’s lower left edge grow progressively darker as the moon moves deeper into the shadow. The moon will be low so there’s the opportunity of photographing the eclipsed moon with interesting foreground features still lit under a bright sky.
The moon is fully within the earth’s shadow at 9:30 MDT and totality begins. The moon is still quite low, it’s exact altitude depending on your precise location; for Kanab it will be only 11° high and for some it will be behind trees and hills. For Kanab that is the time of “nautical twilight” when the sun is 12° below the horizon, and the sky is still fairly bright.
For the next 85 minutes, until 10:54, the moon will be totally eclipsed. As the moon rises higher – and the sun sinks lower – the sky becomes darker and the eclipse becomes more noticeable.
The moon darkens when in the earth’s shadow, but it doesn’t disappear. Sunlight refracted around the edge of the earth and through the earth’s thin atmosphere falls on the moon, and this refracted sunlight is reddened for the same reason that sunrises and sunsets are often red – red wavelengths of light penetrate the atmosphere better than other wavelengths. The moon’s orange or red color is caused by light from all the sunsets and all the sunrises of earth!
At 10:54 p.m. MDT the moon begins to exit the umbra and totality ends. The moon leaves the umbra at 11:56 and for practical purposes the eclipse is over.
An excellent set of graphics set for St. George is at https://www.timeanddate.com/eclipse/in/usa/st-george.
The eclipsed moon occults, or covers, two fairly bright stars, HR 5762 at 9:44 and the pretty double star HR 5756 about 3 minutes later, and it uncovers them at 9:55 and 10:05 respectively; use binoculars or a telescope.
Don’t forget the four planets in the morning sky. Brilliant Venus is unmistakable, but it’s very low and due east. Jupiter is almost as bright, to the upper right of Venus. An equal distance to the upper right of Jupiter is much fainter Mars, and Saturn is much farther to the upper right of Mars. These planets were clustered together recently but are now dispersing.
Through a 2021 grant from the Utah Governor’s Office of Economic Opportunity and the Kane County Office of Tourism, Stellar Vista Observatory provides portable telescopes and tripod mounted binocular kits on loan for free to residents and visitors in Kane County. Enhance your enjoyment of the night sky! For details or to request a loan, visit https://stellarvistaobservatory.org/discover-the-night-sky/ or drop in to the Kane County Office of Tourism.
The Sky Report is presented as a public service by the Stellar Vista Observatory, a nonprofit organization based in Kanab, Utah, which provides opportunities for people to observe, appreciate, and comprehend our starry night sky. Additional information is at www.stellarvistaobservatory.org. Send questions and comments to John@StargazingAdventures.org.