2023 September 18

Every February 2, we wonder if Punxsutawney Phil will see his shadow.

In Saturn’s case, astronomers know some of Saturn’s moons will cast shadows across the planet’s iconic rings every 15 years. This effect only occurs when the planet’s rings are perpendicular to the Sun. The next time this will happen is in May 2025.

Watch as four of Saturn’s moons orbit the planet, based on images taken by the Hubble Space Telescope over a 9.5-hour span in 1995. Enceladus is first and Mimas is close behind. Both of these moons cast small shadows on Saturn, but among the two, only Enceladus’ shadow cuts across the rings. Dione follows next and casts a long shadow across the planet’s rings. About 12 seconds in, the moon Tethys moves swiftly behind the planet toward the right.

Credit: NASA/ESA/STScI.

2023 October 18

Dust and the Western Veil Nebula Image Credit & Copyright: Jiang Wu

Explanation: It’s so big it is easy to miss. The entire Veil Nebula spans six times the diameter of the full moon, but is so dim you need binoculars to see it. The nebula was created about 15,000 years ago when a star in the constellation of the Swan (Cygnus) exploded. The spectacular explosion would have appeared brighter than even Venus for a week - but there is no known record of it. Pictured is the western edge of the still-expanding gas cloud. Notable gas filaments include the Witch’s Broom Nebula on the upper left near the bright foreground star 52 Cygni, and Fleming’s Triangular Wisp (formerly known as Pickering’s Triangle) running diagonally up the image middle. What is rarely imaged – but seen in the featured long exposure across many color bands – is the reflecting brown dust that runs vertically up the image left, dust likely created in the cool atmospheres of massive stars.

∞ Source: apod.nasa.gov/apod/ap231018.html

Picture of the Day!

The Pencil Nebula, 800 light-years away and nearly 5 light-years long, is a small part of the Vela supernova remnant. This supernova shock wave travels through space at over 500,000 kilometers per hour!

Image credit: Helge Buesing

A reminder that our public Spring events start this week!

Public nights are here!

Wed. Oct. 25: The observatory will be closed tonight due to clouds. We'll try to run our Halloween event tomorrow instead, 7:00 - 8:30 pm.

A personal item was found on the observatory decks the day after our public night. If you lost something, check with the Dean's office in the DMF Science and Math Center!

2023 December 29

Shakespeare in Space Image Credit: NASA, ESA, CSA, STScI

Explanation: In 1986, Voyager 2 became the only spacecraft to explore ice giant planet Uranus close up. Still, this newly released image from the NIRCam (Near-Infrared Camera) on the James Webb Space Telescope offers a detailed look at the distant world. The tilted outer planet rotates on its axis once in about 17 hours. Its north pole is presently pointed near our line of sight, offering direct views of its northern hemisphere and a faint but extensive system of rings. Of the giant planet’s 27 known moons, 14 are annotated in the image. The brighter ones show hints of Webb’s characteristic diffraction spikes. And though these worlds of the outer Solar System were unknown in Shakespearean times, all but two of the 27 Uranian moons are named for characters in the English Bard’s plays.

∞ Source: apod.nasa.gov/apod/ap231229.html

Wed. Oct. 22: We'll be open tonight from 7 - 8 pm. We expect some clouds, but we should still be able to catch some nice glimpses of the sky. Saturn is still the star of the show!

Mare Cognitum ("The Sea that has Become Known") with Kuiper crater at the center // l'AstroVan

Mare Cognitum ("The Sea that has Become Known") is the landing sites of several lunar missions. Ranger 7 (1964) impacted here after its mission was finished; Surveyor 3 (1967) and Apollo 12 (1969) landed near its northern shore; and Apollo 14 (1971) landed near this mare as well.

Kuiper crater is named after the Dutch-American astronomy Gerard Kuiper (1905-1973), the father of modern planetary science

2023 October 23

Moon Io from Spacecraft Juno Image Credit: NASA, JPL-Caltech, SwRI, MSSS; Processing & Copyright: Ted Stryk & Fernando García Navarro

Explanation: There goes another one! Volcanoes on Jupiter’s moon Io keep erupting. To investigate, NASA’s robotic Juno spacecraft has begun a series of visits to this very strange moon. Io is about the size of Earth’s moon, but because of gravitational flexing by Jupiter and other moons, Io’s interior gets heated and its surface has become covered with volcanoes. The featured image is from last week’s flyby, passing within 12,000 kilometers above the dangerously active world. The surface of Io is covered with sulfur and frozen sulfur dioxide, making it appear yellow, orange and brown. As hoped, Juno flew by just as a volcano was erupting – with its faint plume visible near the top of the featured image. Studying Io’s volcanoes and plumes helps humanity better understand how Jupiter’s complex system of moons, rings, and auroras interact. Juno is scheduled to make two flybys of Io during the coming months that are almost 10 times closer: one in December and another in February 2024.

∞ Source: apod.nasa.gov/apod/ap231023.html