Roper Mountain Astronomers

Star Gazing Guide

May 15-21, 2020

Bare Dark Sky Observatory

Pictured: Heart Nebula. Photo Credit: Jeremy Bare

Greetings Fellow StarGazers!

If you want to enjoy the last views of our winter and spring night sky objects, you had better get outside early these next few evenings. With sunset around 8:30 pm, and civil twilight ending around 9:15, you can still catch Venus bright in the western sky before she says good-bye until next year. Also, Orion, Perseus, Andromeda, Cassiopeia, Taurus, and all the winter hexagon constellations are going down quickly until late autumn. That’s okay because we still have the Big & Little Dippers, Leo, Virgo, Bootes, Lyra, and several others to observe and enjoy.

Once upon a time, the comings and goings of our constellations were how farmers knew what crops to plant and when. While we no longer need to depend on those signs, we know that the arrival of certain constellations and planets earlier in the eastern night sky means summer and warmer weather are on the way. We have included the Evening Sky Map link below so you can check out what night sky objects are most easily viewed with the naked eye, binoculars, and telescope for May.

EVENING SKY MAP LINK

COMET SWAN

One highlight over the next few weeks will be Comet Swan as it graces our night sky. While Comet Atlas broke apart and didn’t quite live up to expectations, we’re fairly certain Swan is going to deliver an incredible show. Currently, Swan can be seen with the naked eye at around magnitude 5 rapidly moving into the pre-dawn eastern sky (through Pisces) of our southern latitudes (Florida). Reminder: magnitude refers to brightness. The lower the number, the brighter the object. Our naked eye sees magnitude 6 objects and under.

By May 21, Swan should hit a peak brightness of magnitude 2.8 and will become visible in our North Carolina pre-dawn sky. Through the rest of May until June 10 we should easily see (magnitude 5) Swan in the early evening northern sky as it moves toward Capella through Auriga. (See map below). Keep in mind that as Comet Swan moves towards our Sun, the solar wind will cause its tail to become brighter and longer and always pointing away from the Sun. Swan’s cape should present us with spectacular viewing, especially in binoculars and telescopes.

WHAT ARE NEBULAE?

First time viewers of a nebula through a telescope are often disappointed because they expect to see the incredibly colored nebulae that photography delivers. Instead, we generally see shades of white because our eyes are not as sensitive to color as cameras are. Nevertheless most astronomers will agree that nebulae are some of the coolest objects you can look at through a telescope. Nebula in Latin means “cloud” or “fog” and true to name it does often look rather like a “space cloud.” Unlike the clouds on Earth which are made of water vapor, nebulae are clouds of dust, hydrogen, helium, and other gases. Originally astronomers also referred to galaxies as nebulae before they realized the difference. The Andromeda Galaxy was once even called the Andromeda Nebula. Below are basic explanations of different types of nebulae.

Diffuse Nebula – These nebulae have no well defined boundaries. Some of them are “stellar nurseries” where the gas and dust of the nebula begins to clump together until it collapses under its own gravity and ignites forming a star. One of most photographed is the Orion Nebula (M42), which at magnitude 4 can be seen with the naked eye.

Planetary Nebula – These nebulae are formed when stars shed their outer layer leaving behind the core as a white dwarf star. The shed outer layer becomes a shell of gas around the star and radiation from the star causes a glow that allows us to see it. They form in many different shapes and some show significant amounts of color when viewed in a telescope. A BDSO favorite is the bluish colored Ring Nebula (M57) located in Lyra at about magnitude 9.

Supernova Remnant– When a particularly large star uses up the hydrogen fuel at its core, it reaches the end of its life and begins to collapse in on itself. The star’s gas can be heated by the collapse and rebound in a massive stellar explosion called a supernova. The scattered material from this explosion can form a particular type of nebula called a supernova remnant. At magnitude 8.4, the Crab Nebula (M1) was the first nebula to be recognized as a supernova remnant. In fact, the supernova that created it was recorded by Chinese astronomers in 1054. As often as we hear about the possibility of witnessing a supernova, such sightings are quite rare indeed.

The way that we see nebula is another way to classify nebula:

Emission – We see these nebulae because the gas inside it is excited by radiation causing it to glow and emit its own light; kind of like a neon sign.

Reflection – These nebulae have stars inside that are illuminating the surrounding gas and dust which get reflected, allowing us to see them.

Dark – We can’t actually see these nebulae directly. But we can tell they are there because they block our view of something behind it. The biggest dark nebulae are quite prominent and can be seen with your naked eye as when you look at the Milky Way on a clear night. The huge darker patches are where dark nebulae are blocking our view of some of the stars. The two main ones are called the Great Rift and the Coalsack Nebula.

As we close this edition, we want to thank those of you who have sent us words of encouragement and affirmation. We especially love hearing your stories of stargazing with family and friends. Definitely let us know if there is a particular astronomy subject you would like us to cover. We’ll do our best!

Quite often we are asked, “Do you think there is intelligent life out there?” We like Arthur C. Clark’s answer: “Two possibilities exist: Either we are alone in the Universe, or we are not. Both are equally terrifying!”

Keep Looking UP! 

Jeremy & Steve

BDSO Staff

website: mayland.edu/observatory

email: observatory@mayland.edu