Stellar Vista Observatory Sky Report
John Mosley
Jan. 31 – February 6
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 available on this website. Send questions and comments to [email protected].
The sole planet in the evening sky is now Jupiter, which you’ll see low in the west shortly after sunset. Its great brightness lets you see it nearer to the horizon, when we’re looking through more layers of our atmosphere, than nearby stars, none of which are as bright.
On Monday, Jupiter is 14 degrees high in the west 45 minutes after sunset and you’ll easily see it if no structures block your view. On Sunday, it’s 11 degrees high 45 minutes after sunset, so it’s slipping from view and we’ll soon lose it. Be prepared to say good-by to Jupiter later in February.
The planetary action is now in the morning sky where Venus is becoming the brilliant “Morning Star” and Mars is struggling to return to view after a long sojourn behind the sun. Venus is easily visible low in the southeast in morning twilight. Mars is not quite 10 degrees to the right of Venus at a similar height, but it’s precisely 1/100th as bright so it’s hardly conspicuous.
Mercury is there too, near the horizon to the lower left of Venus, this week and next, but most people who want to see Mercury saw it recently in the evening sky.
These three morning planets are in Sagittarius, a decidedly summer constellation, but you can see it in the morning in winter. Next summer, when the earth is on the opposite side of our orbit, you’ll see Sagittarius in the evening.
The moon is in the evening sky beginning Wednesday, and that night you’ll find it only 4 degrees to the left of Jupiter. The width of a finger held at arm’s length is about 2 degrees (remember that!) so they’re quite close and you’ll see both together in a pair of binoculars.
Then the moon is only two days past new, so it’s the slimmest of crescents and it’s only marginally brighter than Jupiter. This is a photo opportunity with the horizon in the same field of view; zoom in a little with your camera. Can you see the lunar seas with your binoculars? You’ll have better luck tomorrow and the next night when the moon is higher.
In the following days, the moon moves through Aquarius and Pisces, huge constellations with no bright stars, so the moon won’t pass near, and be in conjunction with, anything interesting this week.
Notice that the sun sets noticeably later week-by-week (and it rises earlier by the same amount). At the latitude of Southern Utah it now sets one minute later each day. For weeks surrounding the solstice, the time of sunrise and sunset changes very little, but now the rate of change (the greatest difference from one day to the next) is beginning to accelerate.
The rate of change is at maximum at the two equinoxes, and then it slows toward the summer solstice when once again the change is little day-to-day. If you understand sine curves you’ll visualize what is happening.