Some of My Summer Favorites

(Plain Text Version)

In some places, the risk of COVID-19 is low enough that public star parties can resume.  I enjoy observing on my own, but I really enjoy observing with a group of like-minded people.   

Observe Now or Observe Later?

Star parties present a couple of hazards not found elsewhere.  First, social distancing is difficult in the dark.  A dark sky is great for observing, but it makes it hard to see your neighbors.  Secondly, our eyelashes usually touch the eyepiece of the telescope.  This could be a route for a COVID-19 infection. 

Since the guidance of public agencies cannot cover every situation, it is best for the individual to evaluate the situation and decide whether to participate or not.

The Summer Triangle

In the Northern Hemisphere, three bright stars help us to find many interesting objects.  The stars are:

Vega, the brightest of the three.  Vega is white in color, and typically high in the summer sky.  (Arcturus is also very bright, but it is reddish, and lower in the sky.)

Deneb is the bright star closest to Vega.

Altair is a bit brighter than Deneb, and farther away from Vega.  Altair has a medium-bright companion, called Tarazed.

Which One Is Brightest?

This is a trick question!  From our point of view, Vega is obviously the brightest.  But if they are viewed from equal distances, we find that Deneb is one of the most luminous of all known stars.  The visible-light output of Deneb is 950 times that of Vega.  Vega appears brighter because it is much closer to us.  If Vega and Deneb traded places, Deneb would be extremely bright, and Vega would be hard to find in the sky.

The Northern Cross and Much More

The post of the Northern Cross is made of five stars with Deneb at the “top.”  Another two stars make up the crossbar.   This figure is easy to find, and it is a guide to other sights. 

If you are having trouble finding the Milky Way, the Northern Cross is a good place to start.  The Milky Way covers the post of the cross and follows its general direction. 

The star at the bottom of the post is called Albireo.  Albireo is actually two stars close together, called a “double star.”  There are many double stars, but the two stars of Albireo are famous for their beautiful contrasting colors.  A telescope is needed to split Albireo into its two components.  I won’t spoil your first look by saying what the colors appear to be.

To get a perspective on the universe, move the aim of your telescope through any part of the Milky way, and watch the stars go by.  Most of these stars are so far away that you couldn’t reach them in your lifetime, even if you could travel at the speed of light.  And this is only our home galaxy, one of billions!

(to be continued)