August First Light Newsletter 1 message August, 2014 Issue 122 AlachuaAstronomyClub.org North Central Florida's Amateur Astronomy Club Serving Alachua County since 1987 BREAKING NEWS -- ROSETTA HAS JUST ARRIVED AT COMET 67/P Member Member Astronomical League Initiated in late 1993 by Europe and the USA, and launched in 2004, the International Rosetta Mission is an historic first: Send a spacecraft to chase and orbit a comet, ride along as the comet plunges sun ward to learn how a frozen comet transforms by the Sun's warmth, and dispatch a controlled lander to make in situ measurements and make first images Member from a comet's surface. NASA Night Sky Network Ten years later Rosetta has now arrived at Comet 67P/Churyumov- Gerasimenko and just successfully made orbit today, 2014 August 6! Unfortunately, global events have foreshadowed this memorable event and news media have largely ignored this impressive space mission. AAC Member photo: The Rosetta comet mission may be the beginning of a story that will tell more about us -- both about our origins and evolution. (Hence, its name "rosetta" for the black basalt stone with inscriptions giving the first clues to deciphering Egyptian hieroglyphics.) Pictures received over past weeks are remarkable with the latest in the past 24 hours showing awesome and incredible detail including views that show the comet is a connected binary object rotating as a unit in 12 hours. Anyone see the glorious pairing of Venus and Jupiter this morning (2016 Aug. 18)? For images see http://www.esa.int/ spaceinimages/Missions/ Except when Mars is occasionally brighter Rosetta than Jupiter, these two planets are the brightest nighttime sky objects (discounting Example Image (Aug. 6 above). the Moon). Shows a smooth region at base of comet from 130 km My quick photo does not do the scene (80 mi) with 2.4 meter per pixel justice (below). Photo taken at 6:25 a.m. resolution and a EDT when they were 10 degrees above the range of features, including boulders, brightening ENE horizon. Separation was craters and steep cliffs. Note: Comet 67/P 0.3 degrees or slightly more than a half moves in an eccentric moon diameter. This was a bit wider than orbit (eccentricity 0.64) with a 6.45 year their closest approach (0.2 degrees), but period that takes it from just outside that happened several hours earlier (before Jupiter's orbit (5.7 AU) to just outside they rose). My pinkie easily hid both. Earth's orbit (1.2 AU). Neither planet was at greatest brilliancy but Events are being streamed by ESA at: still spectacular: Venus was at magnitude http://sci.esa.int/rosetta/54457-rosetta- -3.85, Jupiter -1.80. (This made Venus 6.6 arrives times brighter looking than Jupiter.) -at-comet-67pc-g---follow-the-event-live If you didn’t get up to see this, you missed For more on this mission see: a beautiful sight. Tomorrow morning their http://www.esa.int/Our_ separation will have increased to 1-1/4 Activities/Space_Science/ degrees. This should still make a neat Rosetta scene. http://rosetta.jpl.nasa.gov/ Howard L. Cohen Howard L Cohen Emeritus Assoc. Professor of Astronomy Department of Astronomy University of Florida Droughts, Floods and the Earth's Gravity, by the GRACE of NASA Space Place article by Dr. Ethan Siegel When you think about gravitation here on Earth, you very likely think about how constant it is, at 9.8 m/s2 (32 ft/s2). Only, that's not quite right. Depending on how thick the Earth's crust is, whether you're slightly closer to or farther from the Earth's center, or what the density of the material beneath you is, you'll experience slight variations in Earth's gravity as large as 0.2%, something you'd need to account for if you were a pendulum-clock-maker. But surprisingly, the amount of water content stored on land in the Earth actually changes the gravity field of where you are by a significant, measurable amount. Over land, water is stored in lakes, rivers, aquifers, soil moisture, snow and glaciers. Even a change of just a few centimeters in the water table of an area can be clearly discerned by our best space-borne mission: NASA's twin Gravity Recovery and Climate Experiment (GRACE) satellites. Since its 2002 launch, GRACE has seen the water-table-equivalent of the United States (and the rest of the world) change significantly over that time. Groundwater supplies are vital for agriculture and provide half of the world's drinking water. Yet GRACE has seen California's central valley and the southern high plains rapidly deplete their groundwater reserves, endangering a significant portion of the nation's food supply. Meanwhile, the upper Missouri River Basin undefined recently home to severe flooding undefined continues to see its water table rise. NASA's GRACE satellites are the only pieces of equipment currently capable of making these global, precision measurements, providing our best knowledge for mitigating these terrestrial changes. Thanks to GRACE, we've been able to quantify the water loss of the Colorado River Basin (65 cubic kilometers), add months to the lead-time water managers have for flood prediction, and better predict the impacts of droughts worldwide. As NASA scientist Matthew Rodell says, "Without GRACE we would have no routine, global measurements of changes in groundwater availability. Other satellites can’t do it, and ground-based monitoring is inadequate." Even though the GRACE satellites are nearing the end of their lives, the GRACE Follow-On satellites will be launched in 2017, providing us with this valuable data far into the future. Although the climate is surely changing, it's water availability, not sea level rise, that's the largest near-term danger, and the most important aspect we can work to understand! Learn more about NASA’s GRACE mission here: http://www.nasa.gov/mission_pages/Grace/ Kids can learn all about launching objects into Earth’s orbit by shooting a (digital) cannonball on NASA’s Space Place website. Check it out at: http://spaceplace.nasa.gov/how-orbits-work/ Image credit: NASA Earth Observatory image by Jesse Allen, using GRACE data provide courtesy of Jay Famigleitti, University of California Irvine and Matthew Rodell, NASA Goddard Space Flight Center. Caption by Holli Riebeek. Kids can test their knowledge about the Sun at NASA’s Space Place: http://spaceplace.nasa.gov/solar-tricktionary/ Schools Outreach & Star Parties Mike Toomey Ivo Rabell In September we have one First I want to thank the youth event scheduled. The Kelly’s for doing a terrific job O2BKids Parent Night feeding and hosting 12 Out on Friday, September 26, members and 6 guests at their 2014. Guests arrive at 7:30 home. They supplied p.m. Telescope set up begins sandwiches, cokes, beer, wine, at 6:30 p.m. at 6680 W. etc. We all appreciated them Newberry Road, Gainesville, for their hospitality. FL 32605. Please note that AAC volunteers can access the observing field through a Even though I was right when predicting the gate located off N.W. 9th Blvd. (a block sky would clear at around 9:15 pm, it did north of RedLobster). Additional details and not last. Within 30 minutes, except for a information can be found on the club's small portion of the southern sky, the clouds website under Events Calendar. took over. We had no rain but a lot of sheet Thanks, Mike lightning to the east of us. Only four members set up their telescopes or cameras. Upcoming Events Howard Cohen took beautiful images of For full details of events, please visit our Milky Way including Scorpius and website's events calendar. Sagittarius. Images are forthcoming. Terry Smiljanich set up his Tom Dobbins telescope and we all got to look at a few open September Public Meeting clusters, globular clusters in both Scorpius and Sagittarius. He also showed Albireo in Tuesday, Sept. 9, 2014, 7-9 p.m. Cygnus. Lisa Eager showed Saturn with its Florida Museum of Natural History moon Titan and what I though was a terrific University of Florida Cultural Plaza Ring Nebula. After spending a long time 3215 Hull Road setting up his terrific telescope, the eastern Gainesville, FL 32611-2710 and western sky clouded up and Paul Coia was not able to star align his telescope to be Join us for an interesting evening when our able to track. I can’t wait until we have a speaker, Dr. Haywood Smith a member of clear sky, star party and be able to look the Astronomy Department at the through his telescope. University of Florida will present The Discovery of Neptune. We all got to see a few satellites sweeping across the sky and a meteor going from International Observe the Moon Night East to West, which Terry said, had a blue tail before it disintegrated. Even though the Saturday, Sept. 6, 2014, 7 p.m. weather hampered viewing after a short Behind Easton Newberry Sports Complex time I believe everyone had a great time 24880 N.W 16th Avenue and some of us didn’t leave until close to Newberry, FL 32660 11:00 pm. Please join the AAC in observing our nearest I want to personally thank all members at celestial neighbor. Open to the public and last night’s Kelly’s Star Party. telescopes provided. Mark Kelly Ron Spink New Members Marie Lucas Terry Smiljanich Welcome to new AAC members! Howard and Marian Cohen Amir and Mary Abdullah John Snyder (Joined June 26) Paul Coia and Laura Wright Lisa Eager Mark Kelly (Joined Jule 27) Margarita Quinteros Patrick Norby (Joined July 9) I also want to thank two guest students that I invited, Matt Given and Morgan Gates.