Welcome to Hank’s July 2023 Astrophotography Blog. I am a member of the Black Hills Astronomical Society (BHAS), and one of our main goals as an organization is community outreach, where we put on public star parties. It really is a thrill to look through your first telescope, find named stars in the sky, and see objects in near real time on a monitor. It’s what we do! Members bring their telescopes and have them available for the public to look through the telescope eye piece at the Moon, planets or other bright objects. Other members are really good at knowing the sky and can point out the visible stars, and what is really cool is when they can show you how to “star hop” from one to the next using some easy to remember clues. For example, if you want to know the angular distance between stars, you can hold your arm outstretched in front of you and your fingers and hand can help you estimate the distance. For example, your pinky is about 1° wide, whereas your fist is about 10° across. If you hold your pinky up to the Moon you can see it is about a half of a degree wide. Check this out:
For a public star party in July I brought my telescope and camera to our Hidden Valley Observatory, outside of Rapid City. Over the course of a couple of hours I showed folks 9 different globular clusters, nebulas and galaxies on my computer monitor. To select the objects that I want to show, I go to https://telescopius.com/. It shows what’s in the night sky for any location, organizes the objects by type, brightness and size, and shows you a picture of what it looks like—very cool! The light from my computer and monitor spoils your night vision, so I must be away from the main event action to not ruin everyone’s night vision, but it gives those who drop by a chance to see objects that aren’t often visible thorough a telescope eyepiece (Tip—If you go to a star party and someone has their computer and monitor on, visit their set-up last, so your eyes don’t lose their night vision). At a star party I may only get just a few minutes of exposure before going to the next object, so the quality is not as good as I usually get when capturing images at my home observatory. Here are the nine objects I slewed to for the star party:
M 4 is the closest Globular Cluster to our solar system, at about 6Kly from us. Even in the smallest telescopes it is a fuzzy ball of light about 1.3 degrees west of the bright star Antares in Scorpius (a little more than a pinky in width on a super clear dark night). It was discovered in 1764 and was the first globular cluster in which individual stars were resolved. It is estimated that it is 12.2 billion years old.
M 13 is about 145 light years in diameter and is about 25 Kly away. Its stars are densely packed, and they sometimes collide to produce new stars. These new stars are known as “blue stragglers.”
M 5, and M 22 are sometimes visible to the naked eye when the skies are very clear, but I’d recommend using a good set of binoculars.
M 16 (the Eagle Nebula that has the Pillars of Creation in the center) and M 8 (the Lagoon Nebula) are fun to show people. Also on display were M 27 (Dumbbell planetary nebula), M 51 (Whirlpool Galaxy—that shows two galaxies coming together), and M 101 (Pinwheel Galaxy with the Supernova that showed up this spring!).
Five other objects captured this month were C 4, C 42, C 47, M 2 and M 15. C 42 (NGC 7006) is a distant globular cluster that resides about 135 Kly away in the Milky Way’s galactic halo. The Milky Way’s diameter is about 100 Kly and its galactic halo is made up of dark matter, gas and sparsely distributed stellar clusters that surrounds the Milky Way. This cluster appears in the 1964 science fiction novel Beyond the Furthest Star by Edgar Rice Burroughs, where it is used as a point of reference by the inhabitants of the planet Poloda to determine the location of the Earth. The story was also told in the DC Comics Tarzan comic books #212-218. Those 1972 20-cent comics now go for about $20. Hmmmmm. To get all 7 issues, that’s $140! Nope, think I’ll have to skip that one.
Sunspots show up periodically on the Sun. So far in 2023 there have been no days without sunspots. In 2022 there was one day without a sunspot. But between 2011 and 2015, however, there were only 3 days with sunspots for over 5 years! Sunspots are areas where the magnetic field is about 2,500 times stronger than Earth’s, much higher than anywhere else on the Sun. Because of the strong magnetic field, the magnetic pressure increases while the surrounding atmospheric pressure decreases. This in turn lowers the temperature relative to its surroundings because the concentrated magnetic field inhibits the flow of hot, new gas from the Sun’s interior (the Sun’s core is about 29,000,000 degrees F!) to the surface. Sunspots tend to occur in pairs that have magnetic fields pointing in opposite directions. A typical spot consists of a dark region called the umbra, surrounded by a lighter region known as the penumbra. The sunspots appear relatively dark because the surrounding surface of the Sun (the photosphere) is about 10,000 degrees F., while the umbra is about 6,300 degrees F. Sunspots are quite large, with an average size being about the diameter of the Earth.
And finally, unlike much of the rest of the Earth it seems, the Black Hills has had pretty mild temperatures, clouds and rain this summer, keeping me from spending many nights out under the stars. One of my pastimes is taking photos of clouds with my iPhone. Here’s one I thought you might enjoy that I took outside our front door. I call it “Elvis is in the building.”
Until next month, Clear Skies! -Hank
