This is Dudley Observatory’s Skywatch Line for Friday, May 8, through Sunday, May 10, written by Sam Salem.

On Friday, Sun rises at 5:40am and sets at 8:04pm; Moon rises at 1:33am and sets at 10:48am. Last-quarter Moon occurs on Saturday at 5:10pm.

The Moon will shine in front of the stars of the constellation Capricornus the Sea Goat this weekend. The stars of Capricornus form a pattern that resembles an arrowhead. Look for them before dawn. The constellation is faint; you’ll need a dark sky to spot it.

Pluto is stationary at 7am on Friday. The dwarf planet is located in Capricornus. It’s very faint and requires large optics to see. The Moon is also nearby, so it won’t be easy to spot it.

Venus, magnitude –3.9, shines in the west-northwest during evening twilight. It now stays in view low above the horizon for about 40 minutes after full dark.

As twilight fades look for Beta Tauri, the second brightest star in the constellation Taurus the Bull, coming into view above Venus. Beta Tauri, officially named “Elnath”, marks the tip of the bull’s northern horn. The name “Elnath” comes from an Arabic word meaning “the butting” of the bull’s horn. Watch Aldebaran coming into view almost twice as far below Venus.

On Friday evening, Venus sits right on the line between Elnath and Aldebaran. On Saturday it will have visibly moved off the line.

Jupiter sits to the upper left of Venus. It shines in the constellation Gemini. Jupiter, magnitude –2.0, shines high in the west in twilight about 35° to Venus’s upper left. Jupiter sinks all evening and sets around 1 am on the west-northwest horizon.

Watch Jupiter and Venus close in toward each other for the next weeks. At their conjunction on June 9th, they’ll pass just 1.6° apart. In a telescope Jupiter is down to 35 arcseconds wide, nearly as small as we ever see it.

This weekend, take the opportunity of the moonless early-evening sky to enjoy two lovely face-on spiral galaxies. The brighter, easier galaxy, is M51, also known as the Whirlpool Galaxy. It’s easy to find. It lies just 3.5° southwest of Alkaid, or Eta Ursae Majoris, the star at the very end of the Big Dipper’s handle. The 11’-wide spiral galaxy is visible as a circular fuzz even in small scopes. A telescope will show more detail. Look for a small, brighter center surrounded by a faint halo. These are the galaxy’s nucleus and spiral arms. The compact, bright spot nearby is NGC 5195, a smaller companion galaxy.

Go back to Alkaid, and move your scope 5.7° northeast to locate M101 or NGC 5457, also known as the Pinwheel Galaxy. Spanning more than 20’, this galaxy is challenging despite its similar brightness to the Whirlpool. The Pinwheel Galaxy is much larger and its glow spreads over a larger area, making it appear artificially dimmer, having low surface brightness. A large scope of 10-12 inches is recommended for the best view of this galaxy’s bright center and faint spiral arms.