Introduction
August was a decent month for stargazing. Hopefully, all of you were able to watch the Perseids near or during its peak. I witnessed a few meteor streaks from this shower, even from light-polluted skies. As mentioned in my mid-month check-in post, I could see the northern lights again during the peak of the Perseids. Potential observers will miss 100% of night sky events if they stay indoors!
September will be another spectacular stargazing month as temperatures continue to decline. While there will not be a significant meteor shower like the Perseids this month, there will be some incredible sights to see. Saturn and Neptune will reach opposition this month, making it the best time to view these planets during 2024. The Autumnal Equinox occurs this month, which coincides with a great time to view the zodiacal light during the early morning hours before sunrise. A partial Lunar Eclipse will also be visible over Utah. In addition to these events, there will be a new comet in the morning sky and a chance for a visible nova!
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| Mercury |
Mercury will be a morning object during most of September. On the first September morning, A thin crescent Moon can be found floating near the tiny innermost planet. Mercury will reach its greatest western elongation on the 4th, making it the best time of year for northern hemisphere observers to view this planet in the morning sky. By the 9th, Mercury and Regulus, the paw of Leo the Lion, will be about 0.5° away from each other. Mercury will continue to rise later, falling closer to the Sun until it reaches superior conjunction on the 30th. Mercury will return to the evening sky in October.
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| Venus |
Venus will continue to hug the western horizon during September like it did in August. If an observer can get to a high elevation and a clear view of the western horizon, they should be able to spot this planet shining brightly in the twilight. A thin crescent Moon can be found close by on the 4th and 5th of this month. Near the 17th of September, Venus and Spica will be close together in the evening sky. Again, a high elevation and clear view of the western horizon will be needed to view the pair.
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| Mars |
Throughout September, Mars will form a triangle with Aldebaran and Betelgeuse, two bright red supergiant stars. As the month begins, the three red points of light will create a right triangle. Less than a week later, Mars will have changed its position to make an isosceles triangle with two equal-length sides. By the 20th, another right triangle will form, followed by an obtuse triangle for the remainder of the month. A last-quarter Moon will join Mars on the 25th in the morning sky. The best time to view the Red Planet will be in the early morning hours when it is high above the western horizon. It will appear small through a telescope, but its size will increase as it nears opposition early next year.
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| Jupiter |
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| Saturn |
Jupiter will be easy to spot between Mars and Aldebaran during September. By the 8th, Jupiter will lie almost directly in the middle between these two red "stars." The Moon will join Jupiter on the 23rd, just 6° away. The best time for aided views of Jupiter will come in the early morning hours, close to 4:00 AM, when this giant planet will be high above the eastern horizon. Several Galilean Moon transits can be viewed throughout the month, so be sure to check out the Moons of Jupiter & Saturn app for Android or JupiterMoons for Apple devices.
Saturn reaches opposition on the 8th of this month. Observers who have been waiting, now is the time to view this planet! The first half of the month will be the best time to view Saturn, as the brightness of the Moon will not interfere. Although the angle of the rings from our Earthly perspective is not ideal, since they are nearly edge-on, views of this ringed planet will still be great! With a small scope, the rings and Titan, the largest moon of Saturn should easily be seen. The Moons of Jupiter & Saturn app for Android or Saturn's Satellites web app can be used to find the locations of several of Saturn's moons. For those with Apple devices, JupiterMoons and SaturnMoons should offer similar results.
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| Neptune |
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| Uranus |
Uranus will rise right around midnight as the month begins and two hours earlier as September comes to a close. This ice giant can be found close to the Pleiades all month, aiding in locating this dim planet. A 75% lit Moon will join Uranus on the 22nd, passing nicely between this ice giant and the Pleiades.
Neptune will rise about 30 minutes after Saturn and will also reach opposition during September. This will occur on the 20th, but an even more spectacular event occurs two days prior. On the 18th, the Moon will pass close to Neptune, and for Utahns, it will occult (pass in front of) this most distant planet. This will occur a couple of minutes after 1:00 AM. I recommend looking at the pair shortly before this time to watch the occultation take place. Neptune will be to the left of the Moon and about halfway between the center of the Moon and the top. A pair of binoculars or a telescope will be required to watch this event.
Equinox, Zodiacal Light, Comets, Nova
Comet Olbers is still hanging around in the evening sky. Looking towards the northwest, just below the bright star Arcturus, Olbers can be found hugging the western horizon. As the month opens, Olbers glows at a dim 9.37 magnitude and will grow dimmer with each passing day. A pair of binoculars, a telescope, or a long exposure image will be required to see this comet as it heads back out to the outer solar system. As Olbers retreats from the Sun, Comet Tsuchinshan-ATLAS will brighten in the morning sky as it approaches the inner solar system. The best views will come in October, when ATLAS may become visible with the unaided eye, but observers may still try to catch a glimpse of this comet later in September. ATLAS can be found just above the eastern horizon shortly before sunrise. A clear view of this horizon will be required.
The Autumnal equinox will occur on the 22nd this year. This is one of two dates during the year when the Sun is directly over the equator and daylight and night hours are of equal length. This is a great time to view the zodiacal light! During the Spring equinox in March, the zodiacal light can be seen shortly after sunset. During the Autumnal equinox, this light is best viewed in the early morning hours before sunrise. An area free of light pollution will be required, and a camera capable of taking long exposures will help bring out this elusive light. I recommend going out a couple of hours before sunrise and looking east. Many planets will be in the sky, and a cone-shaped light, with the wide part against the horizon and a narrow end higher up, should be able to be seen rising from the east all the way to the zenith. It almost looks like an upside-down ice cream cone. The best chance to see the zodiacal light will come in early September when it will be near the New Moon phase.
A partial lunar eclipse will occur on the 17th. In my experience, a partial lunar eclipse does not look much different than any other Full Moon phase. The eclipse will start at 8:12 PM, with the maximum occurring at 8:44. The eclipse will end at 9:15. I personally will not be watching this eclipse due to the underwhelming experience observers can see with partial lunar eclipses. However, I would not be a good astronomer if I did not properly inform my readers of this event!
A nova, one of the only ones that can be predicted, may be visible during September. A star known as T Coronae Borealis, or the Blaze Star, is actually a binary star system comprised of a red giant and a white dwarf. The white dwarf star steals hydrogen from the red giant, increasing the pressure and heat of the white dwarf. After a period of time, approximately 80 years, in this case, the heat and pressure trigger a thermonuclear explosion, which blasts away all of the stolen material, creating a bright outburst that we can safely observe here on Earth. The Blaze Star lies approximately 2700 light years from the Earth in the constellation Corona Borealis. This constellation can be found between Boötes and Hercules in the west after sunset. Look for the red giant Arcturus in the western sky after sunset, and the Blaze Star can be found slightly higher in the sky. When the Blaze Star does brighten, it will only brighten to about 2 magnitude, or about the brightness of Polaris, the Northern Star. Based on recent activity from this star system, the nova is predicted to occur sometime during September. Unfortunately, this is just a prediction, and the event may not happen for several more weeks or even years from now.
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Monthly Breakdown
September 01: Moon passes within 5° of Mercury
September 02: New Moon 🌑September 04: Mercury reaches greatest western elongationSeptember 05: Moon passes within 1.5° of VenusSeptember 08: Saturn reaches oppositionSeptember 11: First Quarter Moon 🌓September 17: Moon passes within 0.5° of SaturnSeptember 17: Full Moon 🌕September 17: Partial Lunar EclipseSeptember 18: Moon occults Neptune at approximately 1:00 AMSeptember 20: Neptune reaches oppositionSeptember 22: Moon passes within 5° of UranusSeptember 22: Autumnal EquinoxSeptember 23: Moon passes within 6° of JupiterSeptember 24: Last Quarter Moon🌗September 25: Moon passes within 5° of MarsSeptember 30: Mercury in superior conjunction
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| Now get outside and look up! |
Planet images were taken by NASA.
Andrew vs. the Cosmos image was taken by Jeff Greenland.The Milky Way and Trees image was taken by Andrew Greenland.
Orion, Taurus, and Pleiades image was taken by Andrew Greenland.
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