September’s Night Sky Notes: Marvelous Moons
Originally published by Night Sky Network.
Title image of Jupiter’s largest moons, from left to right: Io, Europa, Ganymede, Callisto. Credit: NASA
September brings the gas giants Jupiter and Saturn back into view, along with their satellites. And while we organize celebrations to observe our own Moon this month, be sure to grab a telescope or binoculars to see other moons within our Solar System! We recommend observing these moons (and planets!) when they are at their highest in the night sky, to get the best possible unobstructed views.
The More the Merrier
As of September 2024, the ringed planet Saturn has 146 identified moons in its orbit. These celestial bodies range in size; the smallest being a few hundred feet across, to Titan, the second largest moon in our solar system.
The Saturnian system along with various moons around the planet Saturn: Iapetus, Titan, Enceladus, Rhea, Tethys, and Dione. Credit: Stellarium Web
Even at nearly 900 million miles away, Titan can be easily spotted next to Saturn with a 4-inch telescope, under urban and suburban skies, due to its sheer size. With an atmosphere of mostly nitrogen with traces of hydrogen and methane, Titan was briefly explored in 2005 with the Huygens probe as part of the Cassini-Huygens mission, providing more information about the surface of Titan. NASA’s mission Dragonfly is set to explore the surface of Titan in the 2030s.
This mosaic of Saturn’s moon Enceladus was created with images captured by NASA’s Cassini spacecraft on Oct. 9, 2008, after the spacecraft came within about 16 miles (25 kilometers) of the surface of Enceladus. Credit: NASA/JPL/Space Science Institute.
Saturn’s moon Enceladus was also explored by the Cassini mission, revealing plumes of ice that erupt from below the surface, adding to the brilliance of Saturn’s rings. Much like our own Moon, Enceladus remains tidally locked with Saturn, presenting the same side towards its host planet at all times.
The Galilean Gang
The King of the Planets might not have the most moons, but four of Jupiter’s 95 moons are definitely the easiest to see with a small pair of binoculars or a small telescope because they form a clear line. The Galilean Moons – Ganymede, Callisto, Io, and Europa – were first discovered in 1610 and they continue to amaze stargazers across the globe.
The Jovian system: Europa, Io, Ganymede, and Callisto. Credit: Stellarium Web
- Ganymede: largest moon in our solar system, and larger than the planet Mercury, Ganymede has its own magnetic field and a possible saltwater ocean beneath the surface.
- Callisto: this heavily cratered moon is the third largest in our solar system. Although Callisto is the furthest away of the Galilean moons, it only takes 17 days to complete an orbit around Jupiter.
- Io: the closest moon and third largest in this system, Io is an extremely active world, due to the push and pull of Jupiter’s gravity. The volcanic activity of this rocky world is so intense that it can be seen from some of the largest telescopes here on Earth.
- Europa: Jupiter’s smallest moon also happens to be the strongest candidate for a liquid ocean beneath the surface. NASA’s Europa Clipper is set to launch October 2024 and will determine if this moon has conditions suitable to support life.
Be sure to celebrate International Observe the Moon Night here on Earth on September 14, 2024, leading up to the super full moon on September 17th!
Rocket Launches can sometimes be seen in Garrett County. Especially those from Wallops Island.
Originally published by Space.
September
September 16–18: The Air and Space Forces Association’s Air, Space & Cyber Conference will take place this year at the Gaylord National Resort & Convention Center in National Harbor, Md. According to their website, the conference “provides first-class professional military development, facilitates sharing of emerging requirements and technologies, and helps fuel connections that advance the cause of air and space power.” The theme of this year’s conference is “Achieving Decisive Advantage in an Age of Growing Threats”.
September 17: Traditionally, this designation goes to the full moon that occurs closest to the Autumnal (Fall) Equinox. In most years, the Harvest Moon comes in September, but about every four or five years it occurs in October (the next time this will happen will be in 2025). At the peak of the harvest, farmers can work into the night by the light of this moon, which will rise at 10:34 p.m. EDT (0234 on Sept. 18).
September 17-18: The partial lunar eclipse will be visible over Europe, Much of Asia, Africa, North America, South America, the Pacific, the Atlantic, the Indian Ocean, the Arctic, and Antarctica, according to TimeandDate.com. It will begin at 8:41 p.m. EDT (0141 GMT on Sept. 18), the maximum point of the eclipse will occur at 10:44 p.m. EDT (0341 GMT on Sept. 18) and the partial lunar eclipse will end at 12:47 a.m. EDT on Sept. 18 (0547 GMT). The total duration of the partial lunar eclipse is 4 hours and 6 minutes.
September: Blue Origin will launch its New Glenn rocket on its first flight. The rocket stands about 322 feet (98 meters) tall and can send 50 tons (45 metric tons) to low Earth orbit, and will be Blue Origin’s first orbital rocket.
September: The second of two SpaceX Falcon 9 launches of the European Union’s Galileo satellites will take place in September. The missions mark the first times SpaceX has launched EU satellites carrying classified equipment, and the first time in 15 years that Galileo spacecraft launch from a non-European territory.
September 22: The autumnal equinox will occur at 8:44 p.m. EDT (1244 GMT), bringing astronomical autumn in the Northern Hemisphere, and spring in the Southern Hemisphere.
