The Cuyahoga Astronomical Association (CAA) will host a public star party this Saturday (Sept. 9) from 8:00 to 10:00 PM at the Medina County Park District’s at Letha House Park (West). The club’s observatory will be open and CAA members will offer viewing through their personally-owned telescopes.
The weather forecast is looking good for Saturday. If skies are clear, Jupiter, Saturn, and Neptune will be visible at dusk. Later, Uranus, Saturn, and Neptune will be visible.
The waning Gibbous Moon will clear the horizon at 10:15. When the sky grows dark enough, and before moonrise, there about 30 Messier objects visible. Messier objects include such things as brighter star clusters, nebulas, and galaxies.
We had one of our most successful public star parties for the Medina County Park District last night (July 29) at Letha House. I don’t have an exact count, but I think 100 or more guests came for the event under great clear skies and mild temperatures. The parking lot was full. Lots of young families came with children, many of whom got their first look at the Moon, Jupiter, Saturn, and other objects through a telescope.
Waxing Crescent Moon dominated the sky for the CAA’s Public Night. Photo by James Guilford.
Many thanks to all who helped! Observatory Director Jay Reynolds had a busy night showing the night sky with our 12-inch and 8-inch scopes. Education Director Nora Mishey spent the whole evening in the building, talking with folks about her educational astronomy displays, sharing home-baked cookies, and discussing our club. Three platters of Nora’s cookies quickly disappeared.
“First-light” observing with the just-completed eight-inch Meade. Photo by Alan Studt
We had 14 scopes at the event. Two of them were brought by nonmembers who hopefully will join our club. I was busy during the evening talking with people and showing the Moon with my scope, so I may not have a complete list of members who helped. If I missed anyone, please let me know.
Watching the Space Station. Photo by James Guilford.
A big thank you for helping to VP Tim Campbell, Bob Wiersma, James Guilford, Alan Studt, Rich & Nancy Whisler, Bill & Carol Lee, Carl Kudrna, Dave Nuti, Chris Christie, Bruce Lane, Jay Reynolds, Nora Mishey, and me. If you were there and I missed you, please let me know.
This image shows a region in Saturn’s outer B ring. NASA’s Cassini spacecraft viewed this area at a level of detail twice as high as it had ever been observed before. Image Credit: NASA/JPL-Caltech/Space Science Institute
Newly released images showcase the incredible closeness with which NASA’s Cassini spacecraft, now in its “Ring-Grazing” orbits phase, is observing Saturn’s dazzling rings of icy debris.
The views are some of the closest-ever images of the outer parts of the main rings, giving scientists an eagerly awaited opportunity to observe features with names like “straw” and “propellers.” Although Cassini saw these features earlier in the mission, the spacecraft’s current, special orbits are now providing opportunities to see them in greater detail. The new images resolve details as small as 0.3 miles (550 meters), which is on the scale of Earth’s tallest buildings.
Cassini is now about halfway through its penultimate mission phase — 20 orbits that dive past the outer edge of the main ring system. The ring-grazing orbits began last November, and will continue until late April, when Cassini begins its grand finale. During the 22 finale orbits, Cassini will repeatedly plunge through the gap between the rings and Saturn. The first finale plunge is scheduled for April 26.
For now, the veteran spacecraft is shooting past the outer edges of the rings every week, gathering some of its best images of the rings and moons. Already Cassini has sent back the closest-ever views of small moons Daphnis and Pandora.
Some of the structures seen in recent Cassini images have not been visible at this level of detail since the spacecraft arrived at Saturn in mid-2004. At that time, fine details like straw and propellers — which are caused by clumping ring particles and small, embedded moonlets, respectively — had never been seen before. (Although propellers were present in Cassini’s arrival images, they were actually discovered in later analysis, the following year.)
Cassini came a bit closer to the rings during its arrival at Saturn, but the quality of those arrival images (examples: 1, 2, 3) was not as high as in the new views. Those precious few observations only looked out on the backlit side of the rings, and the team chose short exposure times to minimize smearing due to Cassini’s fast motion as it vaulted over the ring plane. This resulted in images that were scientifically stunning, but somewhat dark and noisy.
In contrast, the close views Cassini has begun capturing in its ring-grazing orbits (and soon will capture in its Grand Finale phase) are taking in both the backlit and sunlit side of the rings. Instead of just one brief pass lasting a few hours, Cassini is making several dozen passes during these final months.
“As the person who planned those initial orbit-insertion ring images — which remained our most detailed views of the rings for the past 13 years — I am taken aback by how vastly improved are the details in this new collection,” said Cassini Imaging Team Lead Carolyn Porco, of Space Science Institute, Boulder, Colorado. “How fitting it is that we should go out with the best views of Saturn’s rings we’ve ever collected.”
This graphic shows the closest approaches of Cassini’s final two orbital phases. Ring-grazing orbits are shown in gray (at left); Grand Finale orbits are shown in blue. The orange line shows the spacecraft’s Sept. 2017 final plunge into Saturn. Image credit: NASA/JPL-Caltech
NASA’s Saturn-orbiting Cassini spacecraft has made its first close dive past the outer edges of Saturn’s rings since beginning its penultimate mission phase on Nov. 30.
Cassini crossed through the plane of Saturn’s rings on Dec. 4 at 8:09 AM EST at a distance of approximately 57,000 miles (91,000 kilometers) above Saturn’s cloud tops. This is the approximate location of a faint, dusty ring produced by the planet’s small moons Janus and Epimetheus, and just 6,800 miles (11,000 kilometers) from the center of Saturn’s F ring.
About an hour prior to the ring-plane crossing, the spacecraft performed a short burn of its main engine that lasted about six seconds. About 30 minutes later, as it approached the ring plane, Cassini closed its canopy-like engine cover as a protective measure.
“With this small adjustment to the spacecraft’s trajectory, we’re in excellent shape to make the most of this new phase of the mission,” said Earl Maize, Cassini project manager at NASA’s Jet Propulsion Laboratory, Pasadena, California.
A few hours after the ring-plane crossing, Cassini began a complete scan across the rings with its radio science experiment to study their structure in great detail.
“It’s taken years of planning, but now that we’re finally here, the whole Cassini team is excited to begin studying the data that come from these ring-grazing orbits,” said Linda Spilker, Cassini project scientist at JPL. “This is a remarkable time in what’s already been a thrilling journey.”
Cassini’s imaging cameras obtained views of Saturn about two days before crossing through the ring plane, but not near the time of closest approach. The focus of this first close pass was the engine maneuver and observations by Cassini’s other science instruments. Future dives past the rings will feature some of the mission’s best views of the outer regions of the rings and small, nearby moons.
Each of Cassini’s orbits for the remainder of the mission will last one week. The next pass by the rings’ outer edges is planned for Dec. 11. The ring-grazing orbits — 20 in all — will continue until April 22, when the last close flyby of Saturn’s moon Titan will reshape Cassini’s flight path. With that encounter, Cassini will leap over the rings, making the first of 22 plunges through the 1,500-mile-wide (2,400-kilometer) gap between Saturn and its innermost ring on April 26.
