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THE DAILY ASTRONOMER
Tuesday, July 5, 2022
July 2022 Night Sky Calendar Part II
WEDNESDAY, JULY 13: FULL MOON: SUPERMOON! (BRONZE EVENT!)
Is it all just hype, this "supermoon" notion? Isn't one full moon very like another with little variation? Not really. A full moon that occurs when the moon is at or near perigee, its point of least distance- appears slightly larger (14%) and brighter than a full moon which happens when it is at apogee -its point of greatest distance. This month, the moon reaches perigee at 5:04 a.m. EDT and will be full at 2:37 p.m. EDT.
The image below reveals the size difference between a perigean full moon (Super Moon) and an apogean full moon (Micro Moon.) Were one to observe these moons simultaneously, the difference would be readily observable. However, any full moon looks essentially the same as any other....but, they're not.
We have a nice assortment of July full moon names from which to choose. "Thunder Moon," "Salmon Moon," and "Buck Moon," the last of which refers to the antlers now growing out of the heads of male deer. Celtic names for the July full moon include "Herb Moon," and "Mead Moon."
FRIDAY, JULY 15: MOON NEAR SATURN
Tonight, in the constellation Capricornus, one will see Saturn just north of the waning gibbous moon (94% illuminated). One should expect to see Saturn close to the nearly full moon as the ringed planet will be at opposition on August 14th. (Refer to the "Planet Watch" section.)
SATURDAY, JULY 16: MERCURY AT SUPERIOR SOLAR CONJUNCTION
We recognize two different types of solar conjunction: inferior conjunction, when a planet passes between Earth and the Sun and superior conjunction, when the planet moves to the far side of the Sun relative to Earth. Today, Mercury moves into superior solar conjunction and will then reappear in the western evening sky later this month.
MONDAY, JULY 18: MOON NEAR JUPITER
Tonight one will see Jupiter close to the waning gibbous moon (69% illuminated). Both bodies will rise by 11:30 p.m. Jupiter passes just north of the moon within the constellation Pisces the Fish. They'll both remain in the sky for the remainder of the night.
TUESDAY, JULY 19: PLUTO AT OPPOSITION
Yes, it's true. Pluto isn't visible without a telescope. However, the IAU's dire 2006 pronouncement notwithstanding, Pluto is still a planet and therefore its opposition is noteworthy. Tonight, Earth passes between the Sun and Pluto. We should have placed quotation marks around the word "between," (well, we did that time), because Earth will be 33.5 times farther away from Pluto than it will be from the Sun. Pluto's distance from Earth will approximately equal 3.17 billion miles.
WEDNESDAY, JULY 20: LAST QUARTER MOON
THURSDAY, JULY 21: MOON NEAR MARS
One will see the waning crescent moon (38% illuminated) close to the red planet tonight within the region between the constellations Pisces the fish and Taurus the bull. They'll both rise by 12:15 a.m.
THURSDAY, JULY 21: THE HELIACAL RISING OF BETELGEUSE
A new Betelgeusian cycle begins. Marking Orion the Hunter's eastern shoulder, Betelgeuse serves as the winter sky's prominent red supergiant star. For the last two months, this shoulder star has appeared so close to the Sun in our sky that it hasn't been visible. This morning, Betelgeuse appears for the first time -albeit briefly- since it vanished into the dusk in late May. We refer to this date of reappearance as its heliacal rising.
Let's imagine that you served as a Betelgeuse watcher and your job required you to track Betelgeuse each night. On July 21st, this star rises into view just before the brightening pre-dawn twilight obscures it. The next morning, Betelgeuse rises four minutes earlier, so you'll be able to track it for a bit more than four minutes before it disappears behind the glow. Like all non-circumpolar stars (those that rise and set), Betelgeuse rises four minutes earlier each day as a consequence of Earth's revolutionary motion. By May, Betelgeuse begins the night well over in the western evening sky. On May 21st, it appears briefly in the west just as the dusk twilight dims sufficiently to render it visible. Soon after its appearance, though, Betelgeuse sets. The next night, Betelgeuse will set just before the sky becomes dark enough to make it visible. May 21st is considered its date of heliacal setting. It won't reappear again until July 21st, when the next Betelgeuse cycle begins anew.
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