Jupiter’s Brightest Night

On the evening of September 25th, 2022, the Sun will set after a 12-hour long day, and immediately Jupiter will rise and dominate as the brightest light in Earth’s sky during a 12-hour long night. Several fascinating phenomena converge to make this possible, so let’s explore them together!

The Southern Equinox

Sun at 0° Tropical Libra = Southern Equinox

The reason day and night are equal in late September is that the Sun crosses over the Equator, and heads South. For the Northern Hemisphere, this ends the Summer and begins the Autumn, and Nights begin to grow longer than the days (vice versa for the Southern Hemisphere). This is part of the reason this season is associated with the scales, Libra. So, the Sun will rise around 6:30am, and set around 6:30pm on September 25.

The New Moon

After the Sun, the Moon is the brightest object in the sky, even in its crescent phases, due to how close it is to Earth. Often you will hear stargazers complain when an astronomical event like a meteor shower takes place during a Full Moon, as her Luminous face makes everything else comparatively dimmer. However, on September 25th, it will come into alignment or Conjunction with the Sun, a New Moon, not visible at any part of the equal Day or Night.

The Combustion of Venus (& Mercury)

Morning Star Venus in the Dawn, 15° from the Sun and approaching, August 2022

After the Sun and Moon, Venus is the brightest object in the sky, due to its relative closeness to Earth, and its highly reflective atmosphere. Brightness is described by the term “Apparent Magnitude”, and Venus’ Magnitude ranges from a -3.0 to -5.0 (the lower the brighter). Compare this to the brightest star in our sky, Sirius, with a Magnitude of -1.66, or to Aldebaran, the eye of Taurus, with a Magnitude of +1.0. When up in the sky, its radiance makes it unmistakable.

From left to right: Earth, New Moon, Mercury, Sun, Venus

Venus, as well as the planet Mercury, have an Inferior Orbit to the Earth. This isn’t to say that they are worse! Rather, they orbit at a smaller distance from the Sun. Because of this, from our perspective, neither can escape too far away from our Star before they turn around and head back toward it. This causes them to be visible only before Sunrise, or after Sunset.

The New Moon, Venus, and Mercury all invisible, too near the Sun

However, like the New Moon, when planets or stars are aligned with the Sun, they become invisible at all parts of the day or night. Nothing within 10° is bright enough to penetrate through its intense rays. This occurs twice/orbit for the Inferior planets, when they are on the far side of the Sun (Superior Conjunction), and again on the near side (Inferior Conjunction). This is called “Combustion”, when a celestial body is so close to the Sun, it’s seemingly burned up, and rendered invisible.

On September 25th, Venus and Mercury will both be Combust, with Venus nearing her Superior Conjunction, and Mercury leaving its Inferior Conjunction, neither visible at any part of the equal Day or Night.

Jupiter’s Opposition

Jupiter with the Waning Gibbous Moon, August 2022

After the Luminaries and Venus, Jupiter is the next brightest object in the sky, because even though it is quite far away, its gigantic size is still able to reflect a lot of light back to us. It has a rage of Apparent Magnitude from -1.66 to -3.0, so less than Venus, but greater than Sirius. But unlike Venus and Mercury, Jupiter has a Superior Orbit to Earth’s, so can be seen anywhere in the sky, disconnected from the Sun’s position. It's visible anytime during the night, depending on its position.

Observe how much closer Jupiter is to Earth when on its purple-dot, rather than its Red one

On September 25th, Jupiter will come into Opposition with the Sun, exactly on the other side of the Sky. On the Annulus, you can see this angle as the Purple divots on the outside of the board. Looking more closely, you might see that there is a white divot next to the Earth in that same space; Opposition is the location of the Moon when it is Full. This placement gives a Superior Planet the same quality as the Full Moon, making it as bright as possible, because it is as close as possible!

The Full Chart, September 25, 2022 @ 8:00pm

So, while Opposite the Sun, Jupiter shines at it’s full -3.0 Magnitude, and it also has an opposite schedule to the Sun, rising at Sunset, culminating at the top of the sky at Midnight, and setting at Dawn. With Moon and Venus too close to the Sun to be seen, Jupiter will not have any competition in shining as the brightest point of light through the entirety of the equal night.

Jupiter Culminating at Midnight, between Mars (left/East) and Saturn (right/West)

Conclusion

You don’t have to wait until next week to observe Jupiter in it’s radiant glory! Even now, a little more than a week from the event described above, you can go out and see Jupiter for much of the night. And with only a basic pair of binoculars, it’s 4 large Moons (Io, Europa, Ganymede, & Callisto) will also become visible to you, even if gazing from a large city! Right now, you’ll just have to wait a little while after Sunset for it to rise. If you are up late/early enough, you’ll see the Waning Moon come up in the East as well.

Due to it’s lovely shine, and its elegant 12 year orbit, nearly every culture around the world has associated the planet Jupiter with optimism, luck, and goodness-in-general. It is my hope that you’ll find all these present in your life while Jupiter comes to it’s closest & brightest! ⭕️

📸 Photos for this project were taken at the Exposition Park Rose Garden by USC in Los Angeles 🥀