May 02

What’s Up in the Sky

What’s Up in the Sky – May, 2021

Things Are Looking Up

With all the safety precautions, vaccine news, and conflict over COVID-19, it’s nice to think about a truly non-partisan topic, and astronomy is just that. Most people simply enjoy the night sky without arguing about it. This month offers a number of opportunities to enjoy some peaceful time.

Let’s begin with some planetary observing. Venus and Mercury are visible near the western horizon after sunset with Mars higher above them. Jupiter and Saturn are visible in the southeastern pre-dawn skies, and with sunrise occurring after 6:00 a.m., it is not that difficult to see them if you are an early riser.

The evening planets are not as easily spotted due to their close proximity to the horizon so binoculars are a must. Since a clear view of the horizon is necessary, the best viewing will be along Lake Michigan, and even though Venus will easily be visible to the naked eye, binoculars will be needed to spot Mercury. Look for Mercury alongside the crescent Moon 40 minutes after sunset on May 13. At the same time on Friday and Saturday, the 14th and 15th, you’ll see that the Moon is now higher in the sky and on the later date will be right next to Mars which forms a right triangle with Castor and Pollux, the twins of Gemini.

Keep following these celestial players through the end of the month. Watch as Venus and Mercury reunite on Friday, May 28, when the separation between them will be less than the size of a Full Moon. Speaking of which, on the night of May 25-26, there will be a “Supermoon”, the closest Full Moon of the year.

For those more experienced amateurs who do most of their observing through a telescope, this month is a good opportunity to check out some double stars. Some excellent candidates for telescopic observing include Algieba (Gamma Leonis), Izar (Epsilon Bootes), Kuma (Nu Draconis) and Iota Cancri. For you neophytes, the scientific names of stars are determined by a distinct set of rules. The Greek letter indicates the relative brightness of the star compared to others in a particular constellation and is followed by the Latin plural name. So the well-known star Alpha Centauri is the brightest star in the constellation Centaurus. There are some exceptions where Beta may be brighter than Alpha, but the designation is usually consistent with this rule.

My favorite double star is Epsilon Lyrae, easily split with binoculars, but not conveniently located until later in the summer so keep it in mind. If you’re just starting to observe double stars, you might want to wait a month or two to observe it. I will let you discover why it’s called the “double-double”.

There are two basic types of double stars: binary stars, which orbit each other, and visual doubles, which appear close to each other but are actually far apart, one behind the other. Distinguishing between the two is not easy and requires measuring their actual distances. Look at the Big Dipper and you will notice that the star in the middle of the handle (Mizar) has a slightly dimmer companion right above it (Alcor). That is an optical double as Alcor is actually three light years farther from us than Mizar is. What makes this so interesting is that both are also binary stars, easily viewed up in the sky.

This month in history:

May 05: Alan Shepard becomes first American in space – 1961
May 06: NASA announces that Canada will build the shuttle robot arm – 1975
May 11: First geostationary weather satellite launched – 1974
May 14: Skylab is launched – 1973
May 20: Pioneer-Venus 1 launched – 1978
May 25: President Kennedy gives speech challenging nation to land astronaut on Moon before the end of the decade – 1961
May 29: First experimental test of Einstein’s General Theory of Relativity performed during total solar eclipse – 1919