Did you know you can check out telescopes at the Library?

Orion StarBlast 4.5" TelescopeThanks to a generous donation from the Louisville Astronomical Society, LFPL is excited to offer telescopes for check out at the Southwest Regional Library. The lending period is for one week and is limited to Louisville Free Public Library cardholders in good standing, 18 years or older. Signing a Telescope User Agreement at the time of checkout is required. Go to the Library Catalog to reserve one today.

For more information on the telescope lending program, visit the Southwest Regional Library or call (502) 933-0029.

March in the Sky
By Frank Nelson, Sidewalk Astronomy Coordinator for the Louisville Astronomical Society

Last month, I focused on the constellation of Orion. If you missed it, Orion is still visible in the night sky at sunset. As you look to the south at sunset, the very first star you see in the sky will be Sirius, the Dog Star. Sirius is the brightest star visible from earth (not counting the sun!) and is located in the constellation of Canis Major, the larger of the two hunting dogs trailing behind Orion the Hunter in the sky. Sirius is a star roughly twice the mass of our own sun with a very faint companion, Sirius B or “The Pup.” Sirius B is a difficult object to observe, not because it is dim, but because Sirius itself is some 10,000 times brighter. Sirius B is the closest White Dwarf star to the earth. A White Dwarf star is the core of a star roughly the size of our sun; when stars these sizes die, they get hot and blow off their outer layers, leaving a white-hot cinder that will slow cool over time. If you have a 4” or larger telescope you can try to see Sirius B. Wait for a night where the air is still, and plan on using 100x magnification. The best time to see Sirius B is when the sky is not yet all the way dark; the bright background sky makes the dimmer star easy to see.

At the Southwest Regional Library Star Party, held in Jefferson Memorial Park on March 15, weather permitting, members of the Louisville Astronomical Society will try to show off Sirius B! The LAS will also host events on March 16 and March 22. Check on https://louisville-astro.org for details and directions.

Star map of March skies in Louisville

Looking at the picture of Canis Major, there is one fuzzy object in the “belly” of the dog, a cluster of stars named M41. The “M” stands for Charles Messier, a French comet hunter in the 1750’s-1770’s. He kept finding fuzzy objects in the night sky that were not comets, so he wrote them down and published his list to help other comet hunters. M41 is easy to find with a telescope or pair of binoculars, and from a very dark site it will look like a dense clump of the Milky Way to your unaided eyes. In the center of M41 is a red star that to me looks more yellow-orange.

Speaking of red stars, if you are up for a challenge this month, just off the rear legs of Canis Major is a star named [VY Canis Majoris]( https://en.wikipedia.org/wiki/VY_Canis_Majoris) (VY CMa for short). VY CMa is a very large star called a Red Giant. How large? If you replaced our sun with VY CMa, the red giant’s surface would reach all the way past Jupiter and almost to Saturn, making it one of the largest known stars in our galaxy! My eyes see VY Canis Majoris as a distinctly orange star; some people see it as a more crimson color and photographs show it as a red dot. If Sirius is the collar of the Big Dog, then the bright star Wezen forms the rear hip. From Wezen, in your telescope you will notice a wide crescent of stars to the east (left) about where the letter “n” is in the dark star chart. The two stars at the top of the crescent are blue and yellow. Keep going in that direction, following the loose trail of stars in the chart below. The white star chart is a close in view of the area taken with the free program [Stellarium](https://stellarium.org/).  Most binoculars and finder scopes have a 4-5° field of view so with binoculars, Wezen and VY CMa will be in the same view.  If you hold your thumb at arm’s length, your thumb is about 1° across for comparison.  With a telescope, you will need to look at the star chart below.  You will see a brighter orange-red star, and next to it a fainter, roughly ½ as bright red point of light. VY CMa is the fainter of the two red stars, furthest from Wezen. Congratulations! You can now say that you have seen the biggest known star in the Milky Way! Even in the light pollution of the city you should be able to find VY CMa. Use the two star charts below to find Sirius, Wezen, and VY CMa! Let us know if you found it! While you are already in the area, check out the star labeled Tau (τ CMa). Tau is the brightest of a pretty scattering of stars, best seen with a telescope and higher magnification. If you make it to one of our many events this month (and the weather cooperates) we can help you learn to starhop!

Star map of March skies in Louisville

And finally for March, get up early and look to the east just before sunrise. There will be a very bright “star” that cannot be missed. That is Venus. Above and to your right (south) there will be another bright white “star” that does not twinkle. That is the planet Jupiter. Below Venus is another not quite as bright “star” that does not twinkle; that is the planet Saturn.

Clear skies!



Last Updated: 03/11/2019