Skywatch Line for Friday, March 27, through Sunday, March 29, 2020

This is Dudley Observatory’s Skywatch Line for Friday, March 27, through Sunday, March 29, written by Sam Salem.

On Friday, Sun rises at 6:45am and sets at 7:16pm, the waxing crescent Moon rises at 8:31am and sets at 10:32pm. Moon sits 8 degrees left of Venus on Saturday evening. As night deepens, you’ll find them forming a triangle with the open cluster Pleiades over them. The main belt asteroid Vesta will be positioned less than four finger widths above the Moon.

During the evening on Sunday, in the western sky, the waxing Crescent Moon will be positioned above the large open star cluster known as the Hyades that outlines the triangular face of constellation Taurus, the Bull. The Moon will also sit to the upper right of bright, orange-tinted star Aldebaran. That star, which marks the bull’s left-hand or southerly eye, is less than half as far away as the cluster’s stars. The Moon, Aldebaran, and the Hyades will all fit nicely within the field of view of binoculars.

Venus, at magnitude –4.2, in eastern constellation Pisces, sits high in the west during and after twilight. Venus doesn’t set now until a good 2½ hours after complete dark. In a telescope, Venus appears half lit, and 23 arc-seconds in diameter. It will continue to enlarge in size and wane in phase for the next two months, becoming a dramatically thin crescent in May.

Mars, Jupiter, and Saturn are grouped low in the southeast as dawn begins. Jupiter is by far the brightest and catches your eye first . Little Mars is moving away from Jupiter eastward toward Saturn. Mars is 3 degrees from Saturn this Saturday. They pass each other by 1 degree on Tuesday. Saturn sits 7 degrees lower left of Jupiter.

This weekend, follow Sirius unaided before sunset and follow Vega unaided early into daylight. Sirius, also called the Dog Star, is the brightest star in the Northern Hemisphere’s sky. Its blue-white, –1.4-magnitude glow should be easy to spot in the south as the Sun sets. Sirius A, the star we see easily from Earth, is about twice the mass of the Sun and about 1.7 times as wide. Hidden within its glow is a second, smaller star, called the Pup. This companion, named Sirius B, is a white dwarf smaller than Earth, with the mass of the entire Sun packed into its tiny frame. Sirius B orbits its larger primary roughly once every 50 years. The two are currently more than 10″ apart, a distance that larger amateur instruments at high magnification under excellent atmospheric conditions can discern. The tiny white dwarf is 10 magnitudes fainter than Sirius A.

The Earth Hour takes place this Saturday from 8:30pm to 9:30pm. Earth Hour is a worldwide movement organized by the World Wide Fund for Nature (WWF). The event is held annually encouraging individuals, communities, and businesses to turn off non-essential electric lights, for one hour, from 8:30 to 9:30pm on a specific day towards the end of March, as a symbol of commitment to the planet. It was started as a lights-off event in Sydney, Australia, in 2007. Since then, it has grown to engage more than 7,000 cities and towns across 187 countries and territories to raise awareness for energy consumption and effects on the environment. In light of the latest developments, the Earth Hour global organizing team is recommending all individuals to take part in Earth Hour digitally this year. Go to the website to explore all different ways you can take part online or at home this Earth Hour.

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