StarWatch: Moravian College Astronomy

JULY 2019

JULY STAR MAP | MOON PHASE CALENDAR | STARWATCH INDEX | NIGHT SKY NOTEBOOK

Print Large Sky Charts For 10 p.m. EDT: NORTH | EAST | SOUTH | WEST | ZENITH

Current Solar X-rays:

Current Geomagnetic Field:

lunar phases

1194 JULY 7, 2019: Jupiter and Saturn: Visible Now: The two most massive planets of the solar system, Jupiter and Saturn, are now easily visible in the south (Jupiter) and southeast (Saturn) by 11 p.m. The only problem is that they are very low in the sky, positioned where the sun is near the winter solstice, so relatively good horizons are necessary if you want to observe them. However, outside of the presence of the moon in the sky, Jupiter reigns supreme in brightness, allowing it to be seen easily if buildings or trees are not hiding it. Recently, the media hyped incorrectly the “ease” of seeing with binoculars the four brightest satellites of Jupiter’s 79 moons, and indeed, at least two of them, Ganymede and Callisto, can be observed this way. They are the two outer moons of the four discovered by Galileo in 1609-10 and as a group are called the Galilean satellites. Ganymede is just a little larger than the planet Mercury while Callisto is just a little smaller. They are distinct worlds onto themselves. The problems with seeing these satellites through binoculars are the differences in brightness between Jupiter and its Galilean satellites, their closeness to Jove, obtaining a precise focus for each eye, and most importantly, holding the binoculars steady. Ideally, these satellites need to be at their greatest angular distances from Jupiter. See the box below. If you want to include the other two moons discovered by Galileo, Io and Europa, which are about the size of our moon, you’ll need a small telescope, but virtually any telescope will do. Spotting scopes will work too. Your longest focal length eyepiece, the one with the biggest number, will easily suffice and make it simpler to find the planet because the telescope’s magnification will be at its lowest and its field of view at its greatest. The extra steadiness that even a rickety tripod will create will hold Jupiter secure enough to see its four moons if they are positioned correctly. July 9th is an especially good evening to try your luck in viewing the four Galilean satellites with a small scope. On almost all clear evenings you will see at least three of the four satellites. If you’ve got the scope outside and working, you should also turn it to Saturn. Fainter than Jupiter, but still bright compared to the other stars, lower in the sky and to Jove’s left by about 30 degrees, a small telescope or spotting scope will have absolutely no problem in discerning Saturn’s beautiful rings which are currently tilted back by nearly their greatest amount. If you see a faint starlike object close to Saturn, it will probably be Titan, Saturn’s largest moon. The next few years will be good for watching the God of the Harvest, but gradually our view of Saturn will shift into the ring plane. The exceedingly thin debris field of frozen ice particles will become invisible from Earth, even through large professional telescopes. Next year at this time, Jupiter and Saturn will be only six degrees apart, while Jupiter will be a mere one degree, two lunar diameters, from Pluto. View Jupiter and Saturn now while the weather is still warm and balmy. You won’t regret taking the time to set up your scope and make these observations.

1195

JULY 14, 2019: “We Choose to Go to the Moon…”

I teach a unit on archaeoastronomy focusing on the Ancestral Puebloans who lived and prospered 1000 years ago in what is now Chaco Culture National Historical Park about 95 miles NW of Albuquerque, New Mexico. I recently spent a few days hiking in the park during late spring and was reminded again of the harsh conditions that these Native Americans had to endure. The historic low for Chaco is -38 degrees Fahrenheit. I’ve seen the morning temperatures dip below freezing in late June, and just a month later, soar to 105 degrees F. by mid-afternoon. Today and 1000 years ago, an abundant year for rainfall was 8-inches, most of it falling in a few summer storms, but in most years three to five inches had to suffice. Corn took 95 days to reach maturity in a growing season of only 105 days in length, yet a millennium ago this area had more people living in it than there are today, 50,000 farmsteads with between two and a dozen individuals on each. A Native American once explained that in addition to many other factors the Ancestral Puebloans lived there because it was hard. They could have migrated away to different areas, and indeed, they slowly did when conditions in the early 12th century brought almost no rain for seven years. From the first moment that I set foot in the park in 1988, I was drawn to this remote area of northwestern New Mexico, just like I am drawn to the badlands of Utah which has an equally severe desert climate. Recently, I finally got it when I came across President John F. Kennedy’s September 12, 1962 Rice University speech about America’s commitment to space exploration. “Why some say, the moon? Why choose this as our goal? And they may well ask why climb the highest mountain? Why, 35 years ago fly the Atlantic?... We choose to go to the moon in this decade and do the other things, not because they are easy, but because they are hard, because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one which we intend to win.” Where are the speeches that motivate and bring forth the best in our collective human spirit today? If going to the moon would have been as easy as sitting in front of an electronic device and watching the Kardashians live through another day of reality TV, it would have already been forgotten. Where will the Kardashians be in a thousand years? Where will “That’s one small step for [a] man, one giant leap for mankind” be in 2969? I think very much remembered if we survive this destructive adolescence of the human species. Armstrong, after years of training and several near-death experiences, still gave himself only a 50 percent chance of successfully landing the Eagle onto the moon’s surface. He believed that if the landing went well, the mission had a 90 percent chance of returning successfully to Earth. When I reflect on my own personal achievements, the ones that bring me the most satisfaction are the accomplishments where the outcomes were uncertain, but where perseverance and tenacity won the day. Living in Chaco 1000 years ago was hard but perhaps fulfilling. Living in the badlands of Utah today is certainly not easy, but with surmounting difficulty comes a sense of satisfaction, and with satisfaction comes a sense of participation and community, and with a sense of participation comes the feeling of being alive and playing a small part in the grand design. We chose to go to the moon not because it was easy, but because it was hard. And we were successful; we won. What an accomplishment for all races—all nationalities, for all humankind! Happy 50th Anniversary, Apollo 11!

1196 JULY 24, 2019: NASA’s Other Great Achievements: After the brilliant success of Apollo 11, it was amazing how rapidly the American public lost interest in the human conquest of space. Congress cut funding for the last three missions, 18-20, and NASA once again began focusing efforts on low Earth orbital endeavors. Three missions to America’s first space station, Skylab (1973), were followed by the Apollo-Soyuz Test Project, our first joint cooperation in space with the Russians (1975), but the real focus of NASA’s future ambitions centered on a reusable vehicle, the Space Shuttle (1981-2011). It seemed like a great idea at the time, going to work in space in reusable equipment, but the turnaround period and mission costs far exceeded projections, and NASA was left with an underutilized program that needed a purpose. That was fulfilled in large part by the construction of the International Space Station, another effort that will probably go down in space history as an underachiever for the 150-billion-dollar price tag to date spent for its creation and maintenance. Mostly ignored during this period has been the human exploration of Mars, the next logical step as we venture deeper into space. When the Chinese finally land on the far side of the moon in the next several years, a plan that was robustly proposed to NASA in the early 1970s by Apollo 17 astronaut Harrison Schmidt, the space race will once again reignite, and Mars will become the primary focus. Until then, it appears that NASA’s human direction in space is still uncertain. While our “manned” efforts to explore space have lacked the excitement of the Apollo era, our robotic probes to untangle the mysteries of the solar system and universe have been spectacularly successful. There have been over 250 of them sent beyond Earth orbit since 1957. Pioneer probes went to Jupiter and Saturn, and Voyager extended the boundaries to Uranus and Neptune. Galileo and Juno (ongoing) orbited Jupiter; Cassini with Huygens travelled to Saturn and its giant moon, Titan, with New Horizons to Pluto (continuing). Mariner craft first studied the inner solar system. Then there was Magellan to Venus and Messenger to Mercury and a dozen orbiters and landers which probed and prodded to reveal the secrets of Mars by traversing and circling the Red Planet. SoHo, among other sun-orbiting missions, has been watching Sol for over 23 years and has discovered over 3000 comets, while Dawn has explored the exotic worlds of the dwarf planets, Vesta and Ceres, in the asteroid belt. Deep Impact sent a probe into Comet Tempel 1, and Stardust collected and returned to Earth particles from Comet Wild’s tail while later revisiting Tempel 1. These are just a few of the highlights of the past 50 years. By far the greatest achievement of NASA’s robotic astronomy program has been the Hubble Space Telescope. Launched defective in 1990, repaired and improved by six Space Shuttle missions, it has done more to aid in the exploration and interpretation of our universe than any other single venture. We now are confident about the age of the universe, 13.8 billion years, and that about six billion years ago, space began accelerating because of a positive still undiscovered pressure, which began dominating the universe called dark energy. We can also now understand the quantity of dark and baryonic (regular) matter which populates the universe to create the acceleration that is observed and realize that what we call the visible universe only accounts for less than five percent of the total mass/energy of the cosmos. And as for all of those Hubble photographs; they are as scientifically valuable as they are beautiful to view. Although the human exploration of space after Apollo has been less focused, NASA’s robotic missions have far surpassed all human expectations in cost effectiveness for the valuable information about our universe which they have returned for our analysis on planet Earth.

1197 JULY 28, 2019: Two Bright Fireballs Last Week: On Wednesday, July 24 at 2:44 a.m., a small space rock descended into Earth’s atmosphere at 45,000 miles per hour triggering a spectacular fireball which was seen over Ontario, Canada. Experts say it was the size of a basketball, but from the light show it created, I think it was larger. Eight all sky cameras belonging to the University of Western Ontario recorded the event according to spaceweather.com, allowing for an orbit to be calculated which showed the object came from the asteroid belt. Particles from its terminal burst were calculated to have landed west of the town of Scott Settlement, a forested, swampy, mosquito-ladened, 52-square mile area where the chances of finding something are extremely remote. The American Meteor Society reported 46 eyewitness accounts, mostly from Canada (Ontario and Québec), but also from Michigan, Ohio, Pennsylvania, and New York. Later that same evening at 11:03 p.m., another brilliant fireball was witnessed along the East Coast from Maine to North Carolina with a similar trajectory and reported to the AMS by 684 individuals. It was also recorded by numerous security cameras. No mention of a relationship between these two events has been postulated. Seeing the sudden brilliance of a fireball light up the nighttime sky is a never-forgotten occurrence that I have only experienced one time (in the mid-1970s) when I was observing near Springfield, Vermont. Annually, just outside of town, the Springfield Telescope Makers, Inc. hold a conference at the site of their famous, pink-colored clubhouse with its steep, alpine-shaped roof. Stellafane is attended by hundreds of astronomy enthusiasts interested in making telescopes and observing the heavens. This year’s meeting takes place Thursday through Sunday, August 1-4. Under a clear, dark summer sky, I was actually observing meteors when scores of people began screaming and yelling. As the cacophony grew louder, I sat up in my lawn chair and noticed my elongated shadow moving from left to right against the green, light-splashed grass. Realizing that something was happening behind me, I turned around just in time to catch the last second or so of a sputtering fireball about the brightness of the full moon disappear behind the distant trees. In reality, fragments of the meteorite had not landed nearby, but were calculated to have fallen in Canada. The whole episode lasted maybe five seconds, but that single event made the weekend completely worthwhile. You can go to the American Meteor Society’s website, https://fireball.amsmeteors.org/members/imo/report_intro/ to report a bright fireball, but remember that a lot of events seen in the sky are not related to bright meteors. Here are some guidelines to consider. The fireball should be abnormally bright. If the meteor lasts longer than 10 seconds (30 seconds according to the AMS), it’s not a meteor. I have never seen any meteor event last over five seconds, and I have seen many thousands of shooting stars in my observing career. Don't report a slow moving light, probably a satellite, or blinking lights in pairs crossing the sky. Sometimes short contrails, catching the light from Sol after sundown, are mistaken for bright shooting stars. I’ve examined the AMS fireball report, and it is extremely easy to complete. By doing so, you’ll be adding to a valuable compendium of information which will help to complete the portrait of a very rare event. Keep looking up!