Minnesota Starwatch is a newsletter describing the night sky in the Midwest.
Updated monthly, it is produced by the
Minnesota Starwatch for April 2018
by Deane Morrison
April opens with Mars and Saturn paired in the predawn sky. On the move eastward, Mars passes a mere 1.3 degrees below Saturn on the 2nd. Just 25 days later, the gap has widened to 13 degrees, and Mars keeps right on going. The red planet also brightens dramatically as Earth closes in on it in the race around the sun. The distance between our worlds shortens from 103 million miles on the 1st to 79 million miles by month's end.
Meanwhile, Earth is about to catch up to Jupiter. As we draw nearer, Jupiter rises in the east earlier and earlier—from about three hours after sunset on the 1st to only half an hour after sunset on the 30th. At that point Jupiter will be up nearly all night, sweeping from east to west and clearly dominating the night sky. No wonder Jupiter was named for the king of the gods. Saturn and Mars follow Jupiter's beacon; look to the south an hour or two before dawn to see all three planets.
Now an "evening star" Venus comes out in the sun's afterglow. Late in the month, you may catch Venus and Jupiter shining from opposite horizons, bracketing the early-evening sky with brilliance.
The moon's travels bring it into pairings with all four planets, starting on the 3rd, when a waning moon visits Jupiter. Between the 4th and 5th the moon passes over the brilliant red star Antares, the heart of Scorpius; and on the 7th it hangs close above Saturn and Mars. On the 17th, a young crescent moon of the next cycle makes a pretty pairing with Venus.
On Sunday the 29th, April's full moon arrives at 7:58 p.m. This is so close to the time the moon clears the horizon that it will appear perfectly full at that moment. And that night it's Jupiter's turn to follow a brighter orb across the sky.
With the winter stars heading into the sunset, April evenings belong to the spring constellations. Leo, the lion, prances high in the south after nightfall this month. A backward question mark of stars called the Sickle outlines Leo's head, while a triangle of stars just to the east outlines the hindquarters and tail. The bright star Regulus, marking Leo's heart, shines from the base of the Sickle. About 77 light-years away, Regulus is a multiple star system. Most of its light comes from its biggest star, which is more than 100 times brighter than the sun. It's also one of the fastest-rotating stars; a recent study indicated that it is spinning so fast it is close to flying apart.
The University of Minnesota offers public viewings of the night sky at its Duluth and Twin Cities campuses. For more information and viewing schedules, see:
Duluth, Marshall W. Alworth Planetarium: www.d.umn.edu/planet
Twin Cities, Minnesota Institute for Astrophysics (during fall and spring semesters): www.astro.umn.edu/outreach/pubnight
Check out the astronomy programs at the University of Minnesota's Bell Museum ExploraDome: www.bellmuseum.umn.edu/ForGroups/ExploraDome/index.htm
03/22/18 Contact: Deane Morrison, University Relations, (612) 624-2346,
Find U of M astronomers and links to the world of astronomy at http://www.astro.umn.edu.