Lorraine Rodgers and Aaron Top have laid down a challenge (sort of...). In a recent discussion between some BAS members (Brett T., Lorraine R. and John H.) it was determined that the thinnest new moon sighting (confirmed by image) was over 5 years ago on Feb 3, 2011. That evening, Lorraine and Aaron observed a 21-hour old crescent above the western horizon just east of Sauble Beach (they moved inland to get away from the winds at the shore). The very thin crescent is just visible above the tallest tree branches in Aaron's image below.
So far, this is the thinnest (youngest) crescent moon seen by local amateur astronomers, - an admirable achievement, although it is not a world record. The "official" visual sighting record is held by Steven James O'Meara who spotted a 15 h 32 min moon in May 1990. The youngest moon seen with optical aid is 11 h 40 min by Mohsen G. Mirsaeed of Tehran on Sep 7, 2002. The Sky&Telescope article on thin moons is here. Note that there is an image taken with the Moon at 0.0 hours age, i.e., at the exact moment of New Moon. Remarkable and true! This was done in daytime by Thierry Legault on July 8, 2013. More information here: Youngest Possible New Moon. As an added comment, if the Moon were a perfect sphere, there will always be a thin crescent of light except at the central moment of a total solar eclipse. The Moon is a real world, of curse and has terrain that can reflect light. The S&T article link in the previous paragraph explains this nicely.
The thin moon challenge: the info you need
The table below includes both last crescent and new crescent moon viewing opportunities in the next few months. Data is from Starry Night but do the moon age calculation yourself by working from the time of NM to the time of observation. Do the math yourself, do not rely on a program to do it for you, we have found discrepancies of several hours between different astronomy software programs. Note that not all of those events listed will break the record, but you might want to try for an observation or an image or two with a fatter crescent and earthshine for practice. Note that an observation by a single observer must be confirmed by a second witness to be eligible for the record. Also acceptable is an image of the thin moon in question (with horizon in the view and original camera data intact) and please make sure your camera clock is accurate to the nearest minute or so. Send all reports and/or images to the editor of SGN email@example.com or contact me for more info. Good luck!
I may have been the only one in this area who saw the “mini-moon” (a full moon at apogee) last May 21. No media covered it, but give us a full moon at perigee (coming this Nov 14) and you will see a lot of print about “supermoons."
The term was invented by an astrologer (name withheld to not give undeserved credit) who defined it as “a new or full moon which occurs with the Moon at or near (within 90% of) its closest approach to Earth in a given orbit." Right away there are two problems: first, the moon’s orbit is not a fixed path that repeats exactly month to month so you are taking 90% of a moving target. Arguments then arise as to how many “supermoons” you can get in a year. Secondly, it is very difficult to actually see a new moon; you risk eye damage since new moons are always close to the Sun. Even during solar eclipses when the moon is silhouetted against the Sun you need to use proper solar filters during the partial phases. “Danger, Will Robinson, Danger!”
Orbiting objects would always be the same size if their orbits were perfectly circular, but circular orbits are extremely rare. Our moon follows quite an elliptical path being father away at “apogee” and closer at “perigee”. Furthermore the actual difference between the two varies. For example, on Sep 18 at 1 pm, perigee distance is 361 896 km. Two weeks later (Oct 4 at 7 am) apogee distance is 406 096 km for a difference of 44 200 km. The next three occasions give a difference of 48 801 km in late Oct, 50 045 km in Nov and 47 409 km in Dec. The difference is never the same. The moon’s apparent size does change between the extremes but the 14% range in size is only an average.
So if the moon is closer to the Earth at perigee, shouldn’t it look bigger? Yes, but they are never seen side-by-side. Most people, if they happen to see both, rely on memory to compare the two moon sizes. If you go to the trouble of taking photos, they need to be with exactly the same camera, the same lens, and the moon must be close to the same location on two separate dates. Since the moon’s path across the sky is different in subsequent months, and it’s phase is not synchronized exactly to its orbit, and the weather sometimes works against you, it is not an easy task. I have succeeded getting photos only a few times in many years of trying. (OK, it was not a big priority.)
At the risk of adding to the media hype, the best “supermoon” this year is Nov 14 with perigee less than 3 hours from full moon, -a small and fairly rare time difference. Although the “mini-moon” last May 21 was a media “non-event”, do (“or do not") check out the next “mini-moon” on Jun 8, 2017. Do (“or do not, there is no try") to take pictures of both; this is the only way to really see the difference. Clear skies!
With the current heat wave holding Ontario in its grip, I am reluctant to talk about particles burning up in our atmosphere and adding more heat to the situation. But, rest assured, the extra energy is only going to make for an interesting night of viewing and not raise our local temperature one iota.
I am of course, talking about the annual Perseid meteor shower. These meteors (the more correct name for shooting stars), appear to stream from the head of the constellation Perseus for the same reason that falling snow appears to come from a point in the road ahead of your moving car. Every August, the Earth passes into a stream of particles (most snow-flake size and smaller) left behind by a comet called Swift-Tuttle.
The shower, already underway because the comet debris is rather wide, can be seen from July 17 to Aug 24, but the main peak of activity falls on the nights around Aug 11 to Aug 13. During the darkest hours after the moon sets (12:36 am Aug 11, 1:12 am Aug 12 and 1:52 am Aug 13) you can see shooting stars fall out of the sky at a rate of 90 per hour or more. This number includes all visible meteors over the entire celestial hemisphere so it is not likely that a single observer will see this many, but expect one per minute on average on those nights. Observing in a group of 4 or so, each covering one-quarter of the sky, is a fun way to get close to the maximum number. In addition, some recent predictions indicate that there may be a burst of higher activity during the night that may raise the number to twice that many.
Perseid meteors hit the atmosphere at 60 km/s, or over 200,000 km per hour and are among the fastest travelling meteoroids, -the proper name before they enter the atmosphere. Most other meteor showers’ particles move much slower (if 30 km/s is slow!). In any case, the energy carried by the particles (remember kinetic energy from physics class?) is mostly converted into light when they encounter the thin upper atmosphere which even at 80 to 120 km is still thick enough to act like a brick wall to meteoroids. The rapid deceleration creates a shock wave that heats the particle to incandescence, producing the glowing trail of light we see from the ground. Some Perseids are a bit more massive than average (maybe the size/mass of a grape) and those meteors may leave a glowing train that persists for several seconds. Some of these trains have been seen with binoculars to persist for several minutes. So bring binos if you have a pair.
The diehard meteor watchers of BAS will be watching in the wee hours after midnight from Aug 11 to 13 from the Fox Observatory and the public is welcome to join us. But, any dark site is suitable even if only a part of the sky is visible. Lying out on a lawn chair watching celestial fireworks is a great way to spend time with family and friends and get a break from the daytime heat. Shooting stars really are “cool."
Craters with bright material on dwarf planet Ceres shine in new images from NASA's Dawn mission.
In its lowest-altitude mapping orbit, at a distance of 240 miles (385 kilometers) from Ceres, Dawn has provided scientists with spectacular views of the dwarf planet.
Haulani Crater, with a diameter of 21 miles (34 kilometers), shows evidence of landslides from its crater rim. Smooth material and a central ridge stand out on its floor. An enhanced false-color view allows scientists to gain insight into materials and how they relate to surface morphology. This image shows rays of bluish ejected material. The color blue in such views has been associated with young features on Ceres. [Image below shows it not colour-enhanced].
"Haulani perfectly displays the properties we would expect from a fresh impact into the surface of Ceres. The crater floor is largely free of impacts, and it contrasts sharply in color from older parts of the surface," said Martin Hoffmann, co-investigator on the Dawn framing camera team, based at the Max Planck Institute for Solar System Research, Göttingen, Germany.
The crater's polygonal nature (meaning it resembles a shape made of straight lines) is noteworthy because most craters seen on other planetary bodies, including Earth, are nearly circular. The straight edges of some Cerean craters, including Haulani, result from pre-existing stress patterns and faults beneath the surface.
A hidden treasure on Ceres is the 6-mile-wide (10-kilometer-wide) Oxo Crater, which is the second-brightest feature on Ceres (only Occator's central area is brighter). Oxo lies near the 0 degree meridian that defines the edge of many Ceres maps, making this small feature easy to overlook. Oxo is also unique because of the relatively large "slump" in its crater rim, where a mass of material has dropped below the surface. Dawn science team members are also examining the signatures of minerals on the crater floor, which appear different than elsewhere on Ceres.
"Little Oxo may be poised to make a big contribution to understanding the upper crust of Ceres," said Chris Russell, principal investigator of the mission, based at the University of California, Los Angeles.
Crater rims illuminated by lunar sunrise: These points of light beyond the sunlit cusps of the Moon look like solitary peaks lit by a low Sun, but they are not. They are probably higher elevations of portions of crater walls protruding above the surrounding lunar terrain which consequently catch sunlight. I regularly check the cusps of the illuminated Moon for these features and on Mar 11, there appeared one of the brightest examples I have seen. There are several additional fainter spots as well; I count at least 5.
While there are isolated mountains on the Moon that can catch the rays of the rising sun, they are usually found in maria in the northern hemisphere (Mt. Pico, Mt. Piton, Teneriffe Mtns, etc). There are no lava plains with isolated mountains on the southern polar regions of the Moon. In the south, the Moon presents a profile that is much more rugged than in the north with crater piled on to of crater and only low mountains in crater centres. I tried to determine which feature might be producing these effects from a detailed lunar map and there is more than one candidate but they are all craters and no isolated mountains.
Last September 2, just before midnight local time, villagers in Eastern Turkey were wakened by quite a different shower – rocks from space! The toc-toc-toc of falling meteorites was preceded by a loud sonic boom which shocked some residents out of their beds. In the morning, small black stones were noticed on some of the roofs, on roads and in area gardens and before a few days went by, over 250 samples of space rocks were collected. The village of Saricicek in the province of Bingӧl, north of the border between Syria and Iraq was the main location where an estimated 230 kg of space rocks came down on our planet. That number has been recently revised to under 50 kg, but this is still a hefty mass from space. Still, meteorite falls are not that uncommon, witness another more recent fall form a fireball over Florida on Jan 24. In that one, a more modest amount was collected, only a kilogram or so, but the hunt is still on there.
The most fascinating aspect of the Bingӧl fall, however, is that scientists have now determined that they are a very rare example of meteorite called a “howardite." Howardites come from not just a nameless chunk of space rock out in the asteroid belt, but specifically from Vesta –the second most massive asteroid and the 4th discovered at the start of the 19th century. NASA’s spacecraft Dawn circled Vesta from July 2011 to September 2012 and during that time, the geologic makeup of the asteroid was analyzed from close up. There are even some indications of which craters might have been the source of these meteorites. Only the largest craters would have involved impacts powerful enough to blast fragments into space –pieces that eventually came to Earth on the rooftops of a sleepy village in Turkey.
Now for the Owen Sound connection: A local meteorite collector Mike Tettenborn, managed to get two specimens of the Bingӧl meteorite and he will display them at the Mar 2 meeting of the Bluewater Astronomical Society. That takes place at the Grey Roots Museum in the Delton Becker meeting room starting at 7 pm on Wed March 2. The public is welcome to attend at no charge.
The first 353 million km of the meteorite’s trip from Vesta was special delivery by our solar system’s gravity, the last 9039.17 km to the Grey Roots Museum was by plane, FedEx truck and automobile! Don’t miss seeing it.
A thick blanket of snow covers the earth; and we gardeners dream and plan for the season ahead. We dream of plants.
In Grey County, we astronomers dream too. Our dreams lie not below, but above - high above - the thick blanket of clouds that covers the winter sky. We dream of stars.
Perhaps Grey County astronomers are the most tenacious on earth, given the many missed opportunities for stargazing due to overcast skies or poor “seeing” - but thatʼs no excuse to be idle. Like planning a garden, the long, dreary winter is the perfect time to bone up on your astronomy knowledge; to study, plan, and dream of the summer skies ahead.
If youʼre a beginner, grab a copy of Nightwatch, by famed Canadian astronomer Terence Dickinson, and study the winter constellations. Learn the directions where you live, so when that rare clear sky or “sucker hole” appears, you can grab a coat, a hat, and binoculars, and run out onto the deck to gaze at Orion, the Pleiades, dazzling Capella or brilliant Sirius, without wasting time locating them before the clouds snap shut again.
Download this monthʼs free copy of The Evening Sky Map from www.skymaps.com. This two-page guide is chockfull of helpful information, including a sky chart specific to the current month, and a “Sky Calendar” listing dates of upcoming celestial events of interest that month. Itʼs also got night-sky observing tips; an astronomical glossary (because a “Variable Star” is not a star with mood swings); and lists of objects that can be seen with the naked eye, seen easily with binoculars, and those that need a telescope. All this for the low, low, price of – FREE!
Study the latest SkyNews Magazine (itʼs Canadian, eh?). The January/February issue lists the top 10 sky sights for the year, and reading about them will give you a better understanding of whatʼs coming up so that when the event arrives, youʼll be able to make the most of it (clear skies allowing), including knowing when, where, and how (with what equipment and what company) you can best enjoy it.
Mark your calendar. Make plans. Book a B&B or campsite near a Dark Sky preserve and, like any good gardener, hit the ground running when the opportune weather arrives. And donʼt forget to check our Bluewater Astronomical Society online events calendar. Weʼve got public viewing dates, or join the club and come camping with us on our special BAS weekends.
Dream big, because Grey County is famous for its microclimates, which means, if you donʼt like the weather - go five kilometres down the road and the sky might suddenly be pristine and bursting with stars - so have those binocs with you so you can pull over (somewhere safe), and enjoy.
Sweet starry dreams everyone!