Four planetary conjunctions with the Moon will occur this September! In this article, we’ll tell you how and when to observe these remarkable events.
What does a conjunction with the Moon mean?
In astronomy, a conjunction is an apparent event that occurs when two or more space objects are visible very close to each other. In general, conjunctions take place between the Moon and planets (Venus, Mercury, Mars, Jupiter, or Saturn).
Obviously, planets don’t get closer to the Moon in space — it would indeed cause a significant impact on the Solar System. The space objects only seem to be close in the sky for the observers from the Earth.
How to see a Moon-planet conjunction?
Here is what you need to know in advance:
- Space objects rise and set time for your location. There is a possibility that an object will rise above the horizon during the daytime, so you won’t be able to see it at all.
- The Moon phase. The fully illuminated lunar disk is, without doubt, an exciting view, but it also hides some relatively faint objects that are close to it.
- The space objects’ trajectory across the sky. It will help you to visualize the future movement of space objects.
Remember that depending on your timezone, you might miss the exact moment of conjunction, but you still have a chance to catch a planet close to the Moon.
Use our stargazing apps to quickly learn all the necessary information, like an object’s set and rise times or the Moon phase. Track the space objects’ path across the sky over time to predict their position for your location or find out the name of any bright dot above your head.
September 8: Moon-Mercury conjunction
On September 8, 2021, at 20:18 GMT (4:18 p.m. EDT), the Moon and Mercury will meet in the constellation Virgo. This will be a relatively distant conjunction since the separation between the celestial objects will be 6°31'. For this reason, you should observe the Moon-Mercury conjunction with the naked eye. Don’t use a telescope or binoculars for the observation — a usual field of view of amateur telescopes is from 1° to about 5° (here is how to calculate your telescope’s field of view.
On September 8, the Moon will be 1-day old, so only 3% of the lunar disk will be visible. Shining at a magnitude of 0.0, Mercury will be a difficult target for those who live in the Northern Hemisphere — the sunset glow will hide the smallest planet from our view. Observers from the Southern Hemisphere, don’t miss your chance! For you, the planet will be in its best evening apparition of this year throughout this September. Read more about Mercury in the night sky in our previous article.
September 10: Moon-Venus conjunction
On September 10, 2021, at 02:08 GMT (September 9, 10:08 p.m. EDT), the 15% illuminated Moon will pass 4°04' to the north of dazzling Venus. The beautiful planet is one of the easiest objects to find in the night sky; on the day of conjunction, it will shine at a magnitude of -4.1 in the constellation Virgo together with the Moon.
September 17: Moon-Saturn conjunction
The next conjunction will occur on September 17, 2021, at 02:33 GMT (September 16, 10:33 p.m. EDT). Our bright natural satellite will pass 3°45' to the south of Saturn — both celestial objects will be placed in the constellation Capricornus. The gas giant will be the faintest of the planets visible in the night sky, with a magnitude of only 0.2. Despite this, a keen eye should notice the ringed planet near the 87% illuminated Moon.
September 18: Moon-Jupiter conjunction
If for some reason, you missed the spectacular conjunction of the Moon and Jupiter in August, this is your second chance! On September 18, 2021, at 06:54 GMT (2:54 a.m. EDT), the almost Full (94% illuminated) Moon and bright Jupiter will meet again in our skies. Since August, Jupiter has slightly lost its brightness but remains the second-brightest planet after Venus — the gas planet shines at a magnitude of -2.8.
The bright duo is a perfect observation target due to their position in the sky. Jupiter climbs high into the sky as the darkness falls and remains visible together with the Moon until around 3 a.m. local time. Look for them in the constellation Capricornus and remember to check the weather in advance to make sure that the clouds won’t interfere with your observations.
This was all you needed to know about the planetary conjunctions with the Moon, including the related upcoming events. If you enjoyed the article, share it on social media.
Wishing you clear skies and happy observations!