Introduction and Monthly Reminders
Aside from the occasional cloudy skies and rain showers, which have occurred on the evenings I plan to stargaze, September has ultimately been clear and a great month to be out under the stars. I hope the clear skies will continue and occur on a night that works for me so I can finally use my telescope! I could see Saturn, Jupiter, Mars, and Venus with my unaided eyes. I was also able to experience two confirmed sightings of Starlink. The satellite train is fantastic, but it ruins the night sky.
September will still bring the chance to see many planetary conjunctions with the Moon, the greatest western elongation of Mercury, Venus reaching its greatest brilliance of 2023, the Autumnal equinox, and the newly discovered Nishimura comet. Nishimura recently made its closest approach to the Earth and was visible in the morning sky. The comet will now be visible in the evening sky shortly after sunset. I recommend going to a dark sky location with an unobstructed view of the western horizon to see this comet. Nishimura should be able to be captured with either a smartphone or DSLR camera by taking a long exposure image.
The Sun
Many things have changed since I last did a tour of our solar system, so I decided to do an updated version! Over the next several months, I will highlight the main parts of the solar system in my mid-month posts. This month, I will start with the Sun at the center of our solar system.
Roughly five billion years ago, gas and dust began to coalesce into a small mass. As the mass grew, so did its gravity, pulling in nearly all of the gas and dust from what is known as the solar nebula. The gravity was so great that hydrogen molecules began to fuse together in the core, creating helium. This fusion process generates massive amounts of energy, which is given off as light and heat. The Sun was born.
The Sun is so massive that all of our solar system's planets, asteroids, comets, and other debris could easily fit inside. In fact, the Sun makes up 99.8% of the total mass of our entire solar system! It would take approximately 100 Earths to span across the equator of the Sun and 1.3 million of our tiny planet to fill the volume of our star. To put this into perspective, if the Sun were the size of a basketball, the Earth would be about the size of a small bead. The Earth's gravity prevents anything on the surface from flying away. Similarly, the gravity from the Sun holds our solar system together, causing the planets, asteroids, and comets to orbit this star instead of drifting away. The Earth is only 93 million miles from the Sun, about 8.3 light minutes, but the force of gravity from our star can be felt about two light years away!
The Sun is the largest object in our solar system. Surprisingly, our star is only average in size and brightness compared to other stars. Stars come in different sizes and colors, such as red and blue giants and red and white dwarfs. In a future post, I will go into more detail about the types of stars. The Sun is classified as a yellow dwarf star and has different layers. The layer we see from Earth is known as the photosphere. The photosphere is approximately 250 miles thick and can reach temperatures close to 10,000° Fahrenheit! Above the photosphere is the chromosphere and the corona. All three of these layers make up the Sun's atmosphere. The atmosphere is where we can see solar flares and sunspots.
Like the planets that orbit our star, the Sun orbits the supermassive black hole at the center of the Milky Way Galaxy. The Sun travels about 450,000 miles per hour and completes one full trip around the Milky Way in 230 million years. Like the planets in our solar system, the Sun rotates about an axis. Since the surface of the Sun is not solid like the rocky planets in the solar system, different regions rotate at different speeds. The region near the equator of the Sun completes one rotation every 25 Earth days. The regions near the poles spin a bit slower and complete a full rotation once every 36 Earth days.
Like many planets in our solar system, the Sun has a magnetosphere that creates a magnetic field. The Sun's magnetic field is similar to a bar magnet, with a north and south pole. However, every 11 years or so, the Sun's magnetic field flips, causing the North Pole to become the South and the South Pole to become the North. This 11-year period is known as a solar cycle. Each cycle has a solar minimum when the Sun is typically quiet with little to no sunspots, coronal mass ejections (CMEs), or solar flares and a solar maximum when the Sun is more active. In 1755, scientists began to track and record the solar cycle. We are currently on solar cycle 25 and approaching solar maximum. Many current predictions suggest that the solar maximum will occur in July 2025, while others predict solar maximum will occur at the end of 2024. Either way now is a great time to buy some solar glasses or solar filters for a telescope or binoculars to safely view our star!
Solar glasses and filters are also ideal for any type of solar eclipse. Utahns can view an annular solar eclipse on 14 October 2023. The prime locations will be south of Salt Lake City. Check out this link for Time and Date to find an ideal location. An annular solar eclipse occurs when the Moon is at its greatest distance from the Earth and cannot block the entire disk of the Sun. This leaves part of the Sun exposed and appears as a "ring of fire" in the sky. Next year, North America will experience a total solar eclipse on 08 April. Unfortunately, Utah will not be in the path of totality for this eclipse. Utahns interested in viewing this eclipse will have to travel to an ideal location that can be found on this map from Time and Date.
Now for the bad news. The Sun is going to die...eventually. Scientists predict that our star has lived about half of its life and has another 5 billion years left. The Sun does not have enough mass to explode in a supernova but instead will collapse into a white dwarf. As the Sun runs out of energy, it will expand and turn into a red giant star. When this happens, the Sun will be so large that it will swallow up the inner planets, including the Earth. The Sun will then collapse back down before expanding again. After doing this a limited number of times, our star will finally collapse into a white dwarf star about the size of the Earth. Fortunately, this cycle is billions of years away, so observers are safe to view the Sun for eons to come.
There are currently several missions that are studying the Sun. These include the Parker Solar Probe, Solar Orbiter, SOHO, Solar Dynamics Observatory, and STEREO. Please take the time to visit these websites to learn more about each solar mission. My current favorite mission is the Solar Dynamics Observatory because it shows what the Sun looks like in real-time. This lets me know if today would be a good day to view sunspots before setting up all my gear.
Check back at the beginning of October for my next Monthly Night Sky Report.
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| Now get outside and look up! |
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