Midmonth Check-In: October 2024 and Olbers' Paradox

        

  Introduction and Monthly Reminders   

    October nights have been cool and very pleasant for stargazing. Grab a comfortable chair—a zero-gravity chair is best—and perhaps a hoodie, blanket, gloves, and beanie, and an observer should be set for the night! During the first part of October, I was able to take out the telescope and view Saturn, M13 (Hercules Cluster), NGC 457 (Owl Cluster), NGC 869 and NGC 884 (Double Cluster in Perseus), both Almach and Albireo binary star systems, and the bright stars of the Summer Triangle; Vega, Altair, and Deneb. I attempted several other objects, but they were obstructed or too dim to see from my location. I also attempted to view Comet A3, which was too close to the Sun to view on the attempted nights. I also traveled out to Area 62, one of my favorite locations in the West Desert of Utah. From here, I imaged the Moon, M31 (Andromeda Galaxy), M13 (Hercules Cluster), and M27 (Dumbbell Nebula). Unfortunately, each image of the DSOs contains satellite trails.

    For the remainder of October, I hope to do more imaging and more telescope views. Most importantly, I hope to be able to see Comet A3! As October progresses, Comet A3 will rise higher in the sky while also becoming less bright. but will still be visible with the unaided eye, especially from a dark sky location. Observers can also still enjoy the Orionid Meteor Shower, which peaks on the 21st.    

Olbers' Paradox

   Think of this: Imagine being one of the pesky grasshoppers in my small garden, and you might be able to see past all of the plants to see the lawn. Now imagine you are the same pesky grasshopper but instead are on my more expansive lawn. From here, the grasshopper would only see grass everywhere it looked. Now imagine you are human again, looking up at the night sky. The universe is full of stars, planets, galaxies, and nebulae, yet the night sky is dark and not bright; why? Several scholars have asked this same question, but it was Heinrich Olbers, a German astronomer, who, in 1823, tried to answer this question. 

      For most of history, it has been believed that we live in a Steady-State Universe. This theory is based on three assumptions: first, the universe is uniform; second, it is not expanding; and third, it is infinite in size. A uniform universe is made up of the same stuff everywhere we look. In every direction, there are galaxies, stars, and nebulae. This is like my grasshopper analogy on my lawn. All the grasshopper can see is grass in every direction. Sure, there may be different types of grass or different lengths, but overall, it's uniform.

    The Steady-State Theory of the Universe says that the universe is not expanding. In other words, it's static. It has always been the same size and will always be the same size. Back to the pesky grasshopper analogy, my yard has a fixed size. It is static. An expanding universe would have looked very different billions of years ago and different still billions of years into the future. 

    The Steady-State Universe also says that it is infinite in size. There is no beginning and no end. The universe has always been this way and always will be. This also means that it is infinitely old. Again, it always has been and always will be.

    In a Steady-State Universe, the night sky would appear bright and hot, much like the daytime sky with the Sun overhead. Any astronomer, or any individual for that matter, knows that this is not the case. The sky is obviously black at night, with a splattering of stars across the black canvas of the night sky.

    At least one of the three assumptions that make up the Steady-State Universe theory must be incorrect. Unfortunately, Heinrich Olbers died in 1840 before his paradox could be answered. It wasn't until 1848 that the poet Edgar Allen Poe, in his essay Eureka, suggested that the universe was not yet old enough for the light from all of the stars to have reached us on planet Earth. This contradicted the Steady-State Universe theory, which assumes that the universe is infinitely old. If this were the case, light from every star would have had time to reach us. 

    While Poe's insight may be part of the answer, it wouldn't be until the mid-1920s that an astronomer could help unravel this mystery and answer more questions about our universe. This astronomer's name was Edwin Hubble. I will discuss him more and the solution to Olbers' Paradox next month! 

 

    Check back soon for my next post!

    

Now get outside and look up!