This is Dudley Observatory’s Skywatch Line for Friday, February 8 through Sunday, February 10, written by Sam Salem.
On Friday, the Sun rises at 7:03am and sets at 5:18pm; the waxing crescent Moon rises at 9:05am and sets at 9:00pm. On Sunday evening the crescent Moon is situated roughly six degrees to the left of Mars, high in the west-southwest as twilight fades. Use the Moon to find Mars, which shines as brilliantly as a 1st-magnitude star. Let bright Mars guide you to the faint planet Uranus. Chances are that you won’t spot Uranus with the eye alone. If you have binoculars, aim them at Mars to glimpse at Uranus and Mars in the same binocular field together. Don’t mistake the star Omicron Piscium for Uranus. The star is brighter than Uranus. It makes a nice triangle with Mars and Uranus in a single binocular field. Mars remains in close vicinity of Uranus this upcoming week, giving you an opportunity to use Mars to zoom in on Uranus with binoculars. On Sunday at nightfall, the Moon pretty much makes a straight line with the star Omicron Piscium and Mars, with Omicron Piscium in between the Moon and Mars.
Uranus is arguably the most mysterious planet in the solar system. The ice giant is spinning on its side. Unlike all the other planets, which spin roughly “upright” with their spin axes at close to right angles to their orbits around the Sun, Uranus is tilted by almost a right angle. In Uranus’ summer, its north pole points almost directly towards the Sun. Unlike Saturn, Jupiter, and Neptune, which have horizontal sets of rings around them, Uranus has vertical rings and moons that orbit around its tilted equator. The ice giant also has a surprisingly cold temperature and a messy and off-center magnetic field. Scientists suspect that Uranus was once similar to the other planets in the solar system but was suddenly flipped over. Most researchers believe that Uranus’ spin is the consequence of a dramatic collision. A new research, published in the Astrophysical Journal last year, ran computer models simulating solar system formation events, using a powerful supercomputer, to offer some clues of how Uranus’ mysterious spin could have happened. Another important motivation of the research is to learn about evolution of ice giants to help our understanding of their distant cousin, exo-planets.
Mars, at 0.9-magnitude, is still the lone evening planet. It’s nicely placed at dusk and sets around 11:00pm. At dawn, a trio of planets is arrayed across the southeast. First up, is magnitude –1.9 Jupiter, rising around 3:20am. An hour later, Venus gleaming at magnitude -4.3, reigns as the “morning star”. Last to appear is the magnitude 0.6 Saturn. Still at the very beginning of its apparition, Saturn clears the southeast horizon just before the start of morning twilight, at about 5:15am. Viewing conditions will steadily improve for Jupiter and Saturn as they climb slightly higher each morning, but Venus is gradually losing altitude as it sinks toward its August conjunction with the Sun.
This weekend as the Moon sets around 10pm, the prime winter constellations sit near the meridian. Constellation Canis Major is home of the lovely open cluster M41. The cluster is easy to find. First, locate the brightest star in the night sky, Sirius, or the Dog Star. Sirius gleams brilliantly at magnitude –1.4. Center Sirius in your binoculars or telescope. Then, dip four degrees south to bring M41 into view. If all the cluster members were gathered together in a single point, M41 would shine with the brightness of a 4th magnitude star. The stellar grouping should be dimly visible without optical aid under a dark, country sky. The cluster stands out reasonably well in binoculars even under a moderately light-polluted sky, and it’s a lovely sight in a small scope used with modest magnification. M41 is roughly the same apparent size as the Moon. Too much power spoils the view by narrowing the telescopic field.