Monthly Night Sky Report: September 2023

       Introduction

    August was a great month as far as weather and astronomy are concerned. The Perseids did not disappoint observers and viewing Saturn around its opposition was a treat. Jupiter was also a delight to view as it nears its own opposition. We also experienced two Full Moons during August, which aren't necessarily great for stargazing, but still an extraordinary event for the month.    

    September typically brings cooler temperatures to Utah as well as an increase in stormy weather. Astronomically speaking, September will bring the opposition of Neptune and great views of Saturn, which just reached opposition, and Jupiter, which will reach opposition in early October. Mercury and Venus will inhabit the morning sky with Jupiter being easy to spot in the southwest shortly before sunrise. September also brings the autumnal equinox. The most exciting event will come during the first half of the month when a naked-eye comet will be visible in the early morning sky. Read on for more information!

             

Mercury

     Mercury will move to the morning sky and can be visible just before sunrise. In fact, September will bring the best morning views of Mercury during 2023. The innermost planet will not be visible until about mid-month due to its inferior conjunction with the Sun on the 6th. Mercury will quickly rise above the horizon and decrease in magnitude as it brightens through September. It will reach its greatest western elongation on the 22nd and will shine brightly at magnitude -0.3 on this date. A thin Crescent Moon can be found close by on the 13th. For the observers who are attempting to view all of the planets in a single night, Mercury will be the last target as it rises shortly before the Sun. 

  

Venus

    Venus will likely steal the show from Mercury during September as it begins the month shining brightly at -4.6. By the 19th, Venus will be shining at -4.8 magnitude, its greatest brilliance. A thin Crescent Moon will join Venus in the sky on the 11th, standing just 11° north of the planet. For observers viewing all of the planets in a single night, Venus will be the sixth, or second to last planet.

    

Mars

    Views of Mars will have to come shortly after sunset during September. The Red Planet can be found to the right of Spica, a bright star above the western horizon, around mid-month. On the 16th, a thin crescent Moon will join the Red Planet in the early evening sky. Mars is quickly approaching its November conjunction with the Sun, so grab a view of this planet while you can! For observers interested in viewing all of the planets in a single night, begin with Mars in the west.

Jupiter

Saturn

     

    Jupiter will rise above the eastern horizon shortly before midnight, Utah time, as the month begins. By the end of the month, this gas giant can be found popping above the eastern mountains two hours earlier. The Moon will join Jupiter in the sky early in the month, on the 4th. For the observer viewing all of the planets in a single night, Jupiter should follow Neptune, making this gas giant the fourth planetary target. The Galilean Moons, which can be seen with a pair of binoculars, are sure to delight an observer of any age. A telescope will reveal the cloud bands, the Great Red Spot, and the shadows of the Galilean Moons as they transit the planet.  

    Saturn reached opposition on the 27th of August and will be a spectacular object to view during September. The current angle of Saturn as viewed from Earth is favorable for viewing the rings of this planet. For observers attempting to view all of the planets in a single night, following views of Mars, swing the telescope to the east to view Saturn. A telescope will reveal several of the Ringed Planet's Moons, including bright Titan which has an atmosphere of methane, and Enceladus which has liquid water below an icy surface. I recommend using a favorite sky-viewing app to see where the moons of Saturn are on your particular night of viewing. The Earth's own Moon will join Saturn in the evening sky on the 26th. 

   

       

Neptune

Uranus

    

    The two ice giants can be viewed through a pair of binoculars but will look their best through a telescope. Uranus will rise above the eastern mountains about 30 minutes after Jupiter, making this ice giant the fifth planet to be viewed for observers attempting to view all of the planets in a single night. Uranus will appear as a greenish disk through a telescope. The Moon can be found just 3° above this planet on the 5th.  

    Neptune will rise above the eastern horizon about an hour after Saturn, which is about an hour before Jupiter throughout September. Neptune should be the third planetary target for observers viewing all the planets in a single night. The most distant planet will appear as a blue-gray disk through a telescope. The best time to view Neptune will come on the 19th when this outer planet reaches opposition. Earth's Moon will pass within 2° on the 1st and again on the 28th.     

Potential Naked-Eye Comet 

    

    A recently discovered comet has the potential to become a naked-eye comet. Nishimura, a comet discovered by an amateur Japanese astronomer on 12 August has grabbed the attention of many astronomers. As of this writing, Nishimura is glowing at a dim 8.5 magnitude, which requires a pair of binoculars or a telescope to view. However, this comet is quickly brightening and is expected to reach a magnitude close to 3.4 which puts this in the range that a human eye can detect. Comets are extremely unpredictable due to their composition. Nishimura will be closest to the Earth on the 12th and 13th of September and its closest approach to the Sun on the 17th. The comet will be best viewed a couple of hours before sunrise during the first half of the month. Following the 17th, Nishimura can be seen in the evening sky shortly after sunset. The best chances of viewing this comet will be from a high elevation that provides a clear view of the eastern horizon for the first half of the month, and a clear view of the western horizon during the second half of September. A long exposure of the sky should reveal this comet's blueish-green nucleus and its tail.

   To catch a glimpse of comet Nishimura, look towards the east shortly before sunrise until September 15th. After the 15th of September, gaze towards the west right after sunset. Find a dark sky location with a high elevation and an unobstructed horizon. Using a long-exposure image can capture the comet's color and tail in greater detail.

 

Monthly Breakdown

  

September 01: Moon passes within 2° of Neptune
September 04: Moon passes within 3° of Jupiter
September 05: Moon passes within 3° of Uranus
September 06: Mercury reaches inferior conjunction
September 06: Last Quarter Moon🌗
September 11: Moon passes within 11° of Venus
September 14: New Moon 🌑
September 16: Moon passes within 1° of Mars

September 19: Neptune reaches opposition

September 19: Venus shines at its greatest brilliance
September 22: Mercury reaches greatest western elongation 
September 22: First Quarter Moon 🌓
September 23: Autumnal equinox

September 26: Moon passes within 3° of Saturn

September 28: Moon passes within 2° of Neptune 

September 29: Full Moon 🌕

         

Now get outside and look up!

Planet images were taken by NASA.

Andrew vs. the Cosmos was taken by Jeff Greenland.

    

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.

A composite image of the 2018 Perseids from Astronomy Picture of the Day.

     I will have a new post by the beginning of September so be sure to check back then. Enjoy the rest of the summer and don't forget to look up!

    

Now get outside and look up!