By Pat Beers Block
Welcome to this month’s highlights of enjoyable evening and morning sky events!
The later part of September marks the end of the summer astronomical season that started on June 21, at the time of the summer solstice, and finishes on Sept. 22, at the time of the fall equinox. This summer astronomical season has been one of the rarer ones because this year we encounter four full moons instead of the typical three full moons that appear within a three month season. Recall we had a full moon in June, July, and August; our last summer full moon will occur in September. A typical season has three full moons because a complete moon cycle lasts exactly 29.5 days. It takes a long time for an annual cycle to result in four full moons within an astronomical season because of the varying number of days within a different months in a calendar year. Our next astronomical season during which there will be four full moons will not occur again until August 2032!
So not only is the presence of four full moons within an astronomical season rare, there is an interesting term that is used to describe one of the full moons within this phenomenon. You have no doubt heard about there being a “blue moon” in the night sky. Well, this term has some complexities that you may find interesting. A moon can be considered a “blue moon” under two conditions. The term can be used to identify a second full moon that appears in one month; this is considered a calendar blue moon. A blue moon is a term that is also applied to the third full moon within an astronomical season; in the case of this summer’s astronomical season, August was called not only a Supermoon, but also a “blue moon”. We can understand how calendar and seasonal blue moons can happen by looking at the lunar cycle. A lunar cycle lasts exactly 29.5 days. Given that fact, it’s quite possible to have two full moons when a month is longer than 29.5 days, and no full moon when months are shorter than 29.5 days (e.g. February with 28 days).
This month, the moon will be a key player again in our celestial calendar. Additionally, there are a significant number of planetary, and planet/star conjunction alignments as well as the start of the Orionid meteor shower that will captivate us as we gaze into the morning and evening sky to enjoy them.
The Orionid meteor shower is considered a major (Class 1) shower, however there are few meteors anticipated within an hour this year. It is anticipated that this year’s meteor shower will produce between 10 to 20 meteors, many of which will not be visible due to the waning moon ( American Meteor Society (amsmeteors.org) .
We can expect to see another full moon phase this month that results in a Supermoon. Recall the term Supermoon, as described in Wikipedia, applies to the moon that is closest in its orbit to Earth. The result of this close proximity of moon to Earth is the appearance of a brighter and bigger full moon. This month’s Supermoon marks the second Supermoon for 2024.
Finally, for those of you who like to follow rocket launches, the website Spacelaunchschedule.com provides great information about rockets and other space launches that occur throughout the month.
Now that we have some insight into major events of September, let’s get ready for this month’s celestial excitement by getting your star gazing equipment ready, your cell phones fully charged and linked to Sky Guide, Sky View Lite, or any other star gazing applications that you find useful, and you resting in your favorite viewing spot to witness the magic of the night and early morning skies!
Fun events to view in September: [extracted from Astronomy Calendar of Celestial Events 2024 – Sea and Sky (seasky.org); NASA’s SKYCAL (gsfc.nasa.gov/SKYCAL); In-The-Sky.org calendar; Highpoint Scientific (https://highpointscientific.com); starwalk.space/en/news; and Wikipedia].
Weeks 1 (Sept. 1-7)
The astronomical month starts on Sept. 1 when the moon and Mercury are in conjunction (visually close to one another) and can be viewed early in the morning. Also on this date, Uranus passes through the Pleiades in the early morning hours. It may be difficult to spot Uranus because it appears to be moving backwards (called retrograde motion) so using a telescope for viewing this event is recommended.
On Sept. 2, there will be a new moon. This phase of the moon is a a great time for stargazing since the bright side of the moon faces away from Earth and won’t overshadow celestial bodies and events. Of course, clouds and other weather patterns can always hinder sky views try to be aware of weather predictions as you prepare for your stargazing experience.
On Sept. 4, the moon will be in conjunction with Venus in the evening sky. On the morning of Sept. 5, Mercury is farthest from the Sun and can be seen in the eastern sky. Also on this date, the moon is in the apogee position, a spacial position where the moon is the farthest from Earth. The lunar apogee position reduces the moon’s tidal force on Earth’s tidal waters to its lowest strength.
On Sept. 6, the moon will appear in front of (termed “occultation”) the bright star Spica, of the constellation Virgo, producing a temporary “disappearance” of this star. On Sept. 7, Saturn will be in opposition with Earth, meaning Saturn is at its closest point to Earth and can be seen from Earth from dusk to dawn (Sept. 8).
Week 2 (Sept. 8-14)
On the morning of Sept. 9, Mercury will be close to star Regulus, the brightest start in the Leo constellation and one of the brightest stars in the night sky. The moon is again in occultation with another star on Sept. 10; this time with the red star Antares, of the constellation Scorpius. The moon enters its first quarter on Sept. 11 and appears as a half-moon with the right half of the moon illuminated by the Sun’s rays. This lunar position is very conducive to viewing the sky since the moon’s shine won’t overpower the sky with its light.
Week 3 (Sept. 15-21)
On Sept. 17, the moon is in occultation with Saturn so for a brief time Saturn will appear to disappear from the night sky. A full moon appears on Sept. 17. This full moon is known as the Harvest moon and is the second Supermoon this year. Recall, a moon is known as a Supermoon because it appears much larger and brighter than other lunar events. Provided the sky is devoid of clouds or precipitation, the evening sky will be delightfully illuminated with the entire face of the moon visible and smiling at us with its always friendly and inviting face.
Another lunar event on Sept. 17 is the occurrence of a partial lunar eclipse that begins around 9 p.m. and ends around 11:15 p.m. Partial lunar eclipses are sometimes difficult to see, but with the moon being in its full state on this evening, we might be able to experience the changes in the moon light on this eve.
On Sept. 18, the moon moves into its perigee position, a spacial position where the moon is closest to Earth. The lunar perigee position produces the strongest tidal force on Earth’s tidal waters.
Completing the week, Neptune will be in opposition with Earth on Sept. 20. With Neptune being the planet most distant from Earth, it might be difficult seeing this planet, even with telescopes and sky binoculars. But do give it a try if you have more advanced sky equipment.
Week 4 and 5 (Sept. 22-30)
At 8:45 a.m. on Sept. 22, the autumn equinox will occur. This equinox occurs when the length of the day and night are equal (well, almost). The Sun is located above the Earth’s equator so the split of day and night times is almost equal.
Also on this date, the moon will be in conjunction with Pleiades (the Seven Sisters cluster, also known as Messier 45) in the constellation Taurus.
The moon moves into its last quarter phase on Sept. 23. The moon will be illuminated on the left half of its surface.
The last events of September occur on Sept. 26 when the moon will be in conjunction with the stars Castor and Pollus in the constellation Gemini; Sept. 27 when the moon will be in conjunction with the Beehive star cluster in the constellation Cancer; and Sept. 29 when the moon will be in conjunction with the star Regulus in the constellation Leo.
So ends the celestial highlights for September! Enjoy exploring the September sky and hopefully finding the treasures noted above. Keep looking up to the sky this month; the sky is always changing and it can entertain you for a lifetime. As you become more familiar with planets, stars, and constellations and their locations throughout the year, you are on your way to becoming an expert astronomer who can predict where different celestial bodies might be in the morning and night sky!
Until next month, keep your eyes facing the morning and evening sky to see the wonders of our universe as we Earthlings travel through it!
