A day or two short of the full moon, depending on the libration, on the northwest terminator of the moon you will find a remarkable crater that catches the eye. This is Pythagoras (133km dia.) with beautifully terraced walls and a central peak that casts great shadows across the western side of the crater and the west wall. The extreme near limb presentation of this magnificent crater gives us the opportunity to see just how shallow craters are. When on the terminator near the center of the moon, they look like deep wells but in this case the depth is only 4.8 km or 3.75% of the diameter! Shallow indeed! You can see this for yourself by making a 100mm diameter crater that is only 4mm deep. The large non-circular crater in front of Pythagoras is Babbage (148km) and to it’s left is Oenophiles (70km) and further on is the smaller Markov (43km). To the lower right of Pythagoras is … Continue reading →
About Richard Hill
Richard “Rik” Hill
Born: June 10, 1949 only a few hours after Antares was occulted by a nearly full moon.
My first observation was the May 6th, 1957 transit of Mercury as a schoolboy in a two room schoolhouse in rural Oakland County, Michigan, when a substitute teacher brought a 1.6” Unitron to school and projected an image the sun. She had the wrong day but the sunspots on the Sun fired me up on astronomy at the age of 8! So to that extend, I was a pre-Sputnik amateur astronomer…by 5 months.
I observed through the 1960s, first with the standard 2.4" refractor (Tasco) and later with an RV-6 I bought with money earned mowing lawns and washing cars. I occasionally attended evening astronomy classes at Cranbrook Institute of Science though I did not have good grades in school because I spent all my study time with Sky & Telescope or girls. These poor grades led to my being drafted very quickly after graduation but instead I joined the Navy. In the Navy I served as a radar tech. but was frequently called up by the navigators to help identify stars for sextant fixes. (A very early form of GPS!) A high point in my time in the Navy was when my ship was chosen as the Atlantic backup recovery ship for Apollo 8. We were, of course never used but we got to practice a lot with a dummy capsule and had one of the later Apollo astronauts on board.
After the Navy, I sold the RV-6 to a high school girl who was the only one in the whole Detroit area (then 2 million people) that answered the ad. I was surprised to find she lived in my neighborhood and went to school with my sisters. The young girl and her friend called on me to help them start and astronomy club at their school, the same high school I attended. A year and a half later, in 1974, I married that girl, Dolores, and we're still married. I am committed to a lifetime maintenance contract on the old RV-6!
I joined the Association of Lunar & Planetary Observers (ALPO) and the American Association of Variable Star Observers (AAVSO) in 1975 and have been active, to some degree, in both organizations since. That same year my Dolores and I founded (along with another person) The Sunset Astronomical Society in Midland, Michigan. It is still going strong today.
In 1979, I was hired by Warner & Swasey Obs. (Case Western Reserve Univ.) to operate their Burrell Schmidt telescope being moved from Cleveland, Ohio to Kitt Peak. I worked there for 12 years until the grant was terminated. In 1982 Walter Haas (Director and founder of the ALPO) asked me to found the Solar Section, which I did. (early history at: http://www.alpo-astronomy.org/solarblog/?page_id=209) I left that position in 2004 after one full magnetic solar cycle as Recorder/Coordinator. Hearing of my retirement the ALPO reinstalled me as Coordinator of the Solar Section in 2016. The sun’s instant reaction was to hide all the big sunspots!
In 1992, when Warner & Swasey’s Nat’l Science Foundation grant failed to get renewed I began work with the Planetary Atmospheres and Planetary Occultations groups at the Lunar & Planetary Lab of Univ. of AZ. In these groups I worked with every planet in the solar system and many of the moons. That job lost its funding in Dec. 1999 (common problem in this business) and 20 minutes after being informed of this I was picked up by Steve Larson for work with the Catalina Sky Survey (CSS), an Near Earth Asteroid search project, from which I retired in Oct. 2015. With CSS I have been enjoyed some of my greatest observing challenges but the rewards were high. I discovered thousands of asteroids some that have passed closer than the moon, 27 comets and named a over 120 asteroids.
Now I am working on astronomy at my home observatory, fossils I've collected over 35 years, my bonsai trees, vegetable gardens and the taking in rescue cats.
Center bottom we have the spectacular crater Tycho (diameter 88km) the center of the largest ray system on the Moon that completely wraps around the globe. This is two days after the terminator passed over this crater and already the sun is high enough to show the rays without washing out some of the topographic details. For orientation purposes, the large dark crater at the top is Pitatus. Just below that are two similar sized craters Gauricus (82km) on the right and Wurzelbauer (90km) and off to the right is a much smaller well defined crater with a fairly dark patchy floor, Hell (34km). To the left of Pitatus and you’ll see one of the better double walled craters on the Moon, Hesiodus A (15km) looking like a little bulls-eye target with the small central peak. The parent crater Hesiodus (44km) is above it with a small 5km central crater. Going back to Tycho we can see one of the … Continue reading →
The whole rim of Mare Nectaris is populated with wonderful features. Here we have the south side with the big scarp Rupes Altai below and left of center stretching from the beautiful crater Piccolomini (90km dia) at bottom going all they way up past the large Catarina (104km) some 495km. You can just barely see another pressure ridge, concentric to Mare Nectaris, running from Catharina down south of the large “U” shaped crater above center, Fracastorius (128km). Unfortunately the nice east-west rima that bisects this crater is just beyond the resolution of this image. But there are many secondary craters on its floor and a splattering of them in the upper left covering Beaumont (54km) a little brother to Fracastorius. These secondaries are likely the ejecta from the Theophilus impact to the north which must have been a fantastic sight!Continue reading →
Normally a more foreshortened feature, at this libration we get a good look into Endymion, the large 125km diameter crater just right of center. As lunar night approaches we see the wonderful shadows crawling across its floor. The two large craters below and to the left (west) are Atlas (90km) and the smaller, younger Hercules (71km) with the satellite crater Hercules G (13km) on its floor. Many observers think these two are much alike but actually they are remarkably different with a smooth flat floor in Hercules and rimae, and roughness on the floor of Atlas. Even the eject is very different in the two with Atlas having a thick ejecta blanket that even covers over a much older crate to the north. Above these two is the teardrop shaped crater Keldysh (34km). Below and to the right of Atlas is a ghost crater seen best at this sun angle, Chevallier (54km), with small satellite crater Chevallier B (13km) contained … Continue reading →
Outshone by his big brother Copernicus, seen here in the lower left, the sizeable crater, Eratosthenes (diameter 60km) is nevertheless a very interesting crater with nicely terraced walls, a good central peak cluster and a tight herringbone ejecta blanket surrounding the crater. Seen here Eratosthenes forms a southern anchor to the Montes Apenninus. Between Eratosthenes and Copernicus is an eye catching string of secondary craters from the Copernicus impact event. It takes at least a 3″ telescope to make them out clearly and the right lighting. At the south end of this string is a large ghost crater, Stadius (70km) which stands between Sinus Aestuum to the east (southeast of Eratosthenes) and Mare Insularum below Copernicus to the southwest. On the opposite side of Eratosthenes from Stadius is another ghost crater sitting out in Mare Imbrium. This is Wallace (27km) with a more complete rim on the west side than the east. Notice the twin satellite craters below it Eratosthenes … Continue reading →
Something a little different this time to demonstrate what libration is and how it can be used to advantage. Here we have two images of the region from the crater Janssen looking east. Janssen is the largely ruined 196km diameter polygonal crater near the terminator in the center top of each of the two images in this montage. To the right of the center of this crater is a smaller crater, Fabricius (80km) with an odd mountain range on its floor. To the right of this is the slightly larger Metius (90km) and farther on the trench that is Vallis Rheita some 515km long. Below Janssen are two overlapping craters, the top one being Steinheil (70km) laying on top of Watt (68km). Notice that in the image on the right you see a lot more terrain between Watt and the limb. This is what a “favorable libration” can do for you and why you need to pay attention to that. … Continue reading →
This is a crowded highland region on the moon east of Tycho and Clavius. The large crater on the terminator with the great dramatic shadows on is floor is Maginus (168km diameter) with its tiny offset central peaks. Below center is a crater with a pronounced central peak, Lilus (63km) and to the lower right of it is Jacobi (70km) with a bunch of secondary craters on its floor. In the upper right corner of this image is half of the large crater Maurolycus (117km). Notice the crater to the left, Faraday (71km). On the lower left crater wall is a particularly polygonal crater Faraday C (30km) with a curious floor infilled with ejecta from another nearby impact. The concentric depression on the left (west) side of this crater consists of at least 3 merged craters again overlain by ejecta looking like thumbprints in the lunar surface. Moving south from Maurolycus is the crater Barocius (85km) with a curious upper … Continue reading →
The moon is almost full and it seems like there is little to see. But on the southwest terminator is a grouping of craters that lead us to one of the longest cracks on the Moon. Near the top of this image are two overlapping craters. The one on top is Sirsalis (43km diameter). You will notice a rima running north-south just to the right of it. This is, appropriately enough, Rimae Sirsalis one main rima with several smaller, shorter, thinner ones on the side. The main rima is 309km long, its southern end in shadow here and the northern end of the top of this image. Just to the right of the nameplate on this image is the faintest traces of the upper edge of a crater wall. This is the crater Cruger (48km) with the satellite crater Cruger A (27km) the sharp crater next to the rima. Further on in the same direction is a shallow flat bottomed … Continue reading →
Here we have the east coast of Mare Nectaris. There are some real treats here. The wonderful keyhole shaped crater above center is Gutenberg (77km dia) with smaller Gutenberg C (45km) forming the keyhole shape to the south. To the north are the Rimae Gutenberg looking like three roughly parallel scratch marks heading off to the northwest. Michael Collins got great images of these rimae from the Apollo 11 command module under the file name AS11-42-6313. Then east of Gutenberg is the oddly shaped crater Goclenius (56km) with Rima Goclenius stretching from its north wall some 247 km north to Gutenberg E (28km) the broken crater that intrudes on the northeast wall of Gutenberg. Slightly north and to the west on the terminator, is the shadow filled crater Capella (51km). Very dramatic mountains and formations here can be seen as the sun rises further. To the southwest of Gutenberg is a small but interesting crater Guadibert (34km) just a ring … Continue reading →
Our best observing weather is when the days are hot, the evenings warm and still. The colongitude was just right so this was a good night toget a look at the famous “X” on the moon. Can you see it on the terminator? It only lasts for and hour or so. Here’s how you get there. The area below center of this image is dominated by the two circular pools of darkness that are Aliacensis (82km diameter), lower, and Werner (71km) above. A line between the centers of these two craters lead to the “X” formed by the walls of Blanchinus, La Caille, Purbach and several smaller features. Above Aliacensus and Werner is a nice flat floored crater, Apianus (65km) and further above that is a smaller crater Playfair (49km). Near the top of the image is a pair of craters Azophi (49km) and above it is the irregular Abenezra (43km) with Geber (46km) partially cut off by the edge … Continue reading →
The monster crater here is Gassendi (114km diameter), a landmark for this colongitude on the north shore of Mare Humorum, the “Sea of Moisture”. Gassendi was flooded during the same even that created the mare so we only see the tops of what once were magnificent central peaks. The faulted floor is always a enjoyable but I particularly like the detail in the walls of the crater as they catch these early rays of the rising sun. Note the two notches in Gassendi’s wall at about the 11 o’clock position. On LROC Quick Map they appear to be to impacts through the mountains giving the appearance at this lighting of being parallel rimae. The nice central peaks and rimae on the floor are provide a rich field for examination. There are 3 main rimae that diverge from a point to the east of the central peaks. Between two of them is a small crater, Gassendi N (3km). The rima on … Continue reading →
Our best observing weather in southern AZ is when the days are hot, the evenings warm and still. The colongitude was just right so this was a good night to get a look at the famous “X” on the moon. Can you see it on the terminator? It only lasts for and hour or so. Here’s how you get there. The area below center of this image is dominated by the two circular pools of darkness that are Aliacensis (82km diameter), lower, and Werner (71km) above. A line between the centers of these two craters lead to the “X” formed by the walls of Blanchinus, La Caille, Purbach and several smaller features. Above Aliacensis and Werner is a nice flat floored crater, Apianus (65km) and further above that is a smaller crater Playfair (49km). Near the top of the image is a pair of craters Azophi (49km) and above it is the irregular Abenezra (43km) with Geber (46km) partially cut … Continue reading →