Cosmic Lure: Midmonth Check-In: August 2023 and Meteor Showers

Introduction and Monthly Reminders

The first half of August was great for stargazing! I spent the first part of the month learning how to take a night sky timelapse with my DSLR. My main purpose for doing this is to try to capture as many of the Perseid Meteors as I can. I also spent the first week cleaning my telescope and getting it ready for a night out under the stars. I can't believe it's been over three years since I've used it! I hope that many of my readers were able to get out under the stars as summer comes to an end. I also hope that the Perseid Meteor Shower was visible and enjoyable from wherever it was observed.

August will still offer observers the chance to view the wonders of the universe under a Moon-Free sky on the 16th. There will also be another Full Moon on the last day of the month. Since this will be the second Full Moon in August, it will be known as a Blue Moon. And coincidentally, the Moon will be found closer to Earth than a normal Full Moon, making it a Super Moon. So in reality, this will be known as a Super Blue Moon! Saturn will reach opposition on the 27th, making this a great time to view the ringed planet.

Meteor Showers

Due to the peak of the wildly popular Perseid Meteor Shower, I decided to remind my readers what causes meteor showers, how we can predict when they will peak, and how they get their names. Shooting stars, or meteors, are caused by small pieces of space debris burning up in Earth's atmosphere. Occasionally, a larger piece of debris can enter the atmosphere and cause a fireball to streak across the sky. Typically, the debris that causes a meteor is about the size of a small pebble. The brighter "fireballs" are caused by debris about the size of a softball or basketball. During a randomly chosen night, an observer can expect to see an average of seven meteors per hour. However, during the peak of a meteor shower, such as the Perseids, observers can expect to see over 100 meteors per hour. This large increase is caused by the Earth plowing through a debris field that is left by a comet as it enters the inner solar system. The best Earthly example that comes to mind is driving through a swarm of insects. On an average day, one might get a few bug splats on their windshield, but when driving through a swarm, the windshield is often coated with bugs.

Predicting meteor showers is really quite simple. The Earth has an orbital path around the Sun which is completed once a year. For example, on 12 August 2023, the Earth is in roughly the same position in its orbit as it was on 12 August 2022 and back in 2021 and even 1972. This means that on the 224th day of each year, the Earth will pass through the debris left by a comet, in this case Swift-Tuttle, causing a meteor shower. Again, imagine a car driving along a road. The car may approach and drive through a railroad crossing. Now, let the car represent the Earth, the road represents the orbital path of the Earth as it moves around the Sun, and the railroad crossing represents the path a comet took around the Sun.

During a timelapse or a long exposure image of a meteor shower, the meteors will appear to radiate from a certain point in the sky. The Perseids, for example, appear to radiate from the constellation of Perseus. Likewise, the Orionind Meteor Shower appears to radiate from Orion, so it's easy to see how the meteor showers get their names. Of course, we know that the meteors don't actually come from these constellations since the stars are hundreds or thousands of light-years from the Earth. The constellations are just background stars as the Earth passes through the debris left over from a passing comet. A timelapse or long-exposure image can show quite a few meteors. These images remind me of driving through a snowstorm and watching the snowflakes as they approach the windshield. The Earth represents the inside of the car, the sky represents the windshield of the car, and the meteors are the snowflakes.

Below is one of my favorite images that I have captured of a meteor. This long exposure was taken in 2021 and shows a blue meteor streak (right), an aircraft (lower left), Polaris (near center), the Milky Way Band (top right to middle left), and star spin from the rotation of the Earth.

Blue meteor streak, Polaris, and star spin.

I found the following image on the Astronomy Picture of the Day website that shows a composite image of the Perseids from 2018. This image illustrates my snowstorm analogy pretty well.