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Today I am posting some pictures of what I think is the most beautiful deep space object. The Sombrero Galaxy (M104) is a nearby galaxy which is visible edge-on in the constellation of Virgo. Actually, calling it an object might be a bit misleading since M104 consists of more than 400 billion stars–not to mention numerous associated globular clusters, innumerable planets, immense clouds of gas & gas, and a supermassive black hole which lies in the center. The black hole in the center of M104 isn’t a mild mannered & quiescent black hole like the one in the center of the Milky Way either. Based on the speed of revolution of the stars near the middle of M104, astronomers calculate that the central black hole has a billion times the mass of the sun.
In cosmic terms, the Sombrero galaxy is nearby—which is to say it is merely 28-odd million light years away. The galaxy was discovered in the late eighteenth century by Pierre Méchain . Other prominent 18th century astronomers subsequently observed and studied M104, including Charles Messier (which is the reason the galaxy is included in the “Messier” catalog and has a M-designation) and the redoubtable William Herschel who noted a “dark-stratum” bounding the luminous central bulge. We now know that this ring around M104 is a toroid dust lane of vast proportions which halos the galaxy. Astronomers initially thought that the Sombrero Galaxy was an unbarred spiral galaxy, but thanks to observations from NASA’s Spitzer space telescope (an infrared scope orbiting Earth), the scientific community has revised their estimation of its size upward. It lies somewhere between a spiral galaxy and an elliptical galaxy. In other words, when you look at the Sombrero Galaxy, you are looking at something vast beyond human comprehension—a galaxy bigger than our own filled with who knows what things we will never know. And yet if you expand the Hubble photo at the top of this post, you will see that all of the little stars shining around M104 are other galaxies farther away.
Discovered by Sir William Herschel in 1781, the seventh planet in our solar system is named for the Greek deity Uranus, the original skygod of the Greek cosmology. In classical myth Uranus was castrated and supplanted by his youngest son Cronus (Saturn) who then fell before Zeus (Jupiter) and indeed, the third largest planet in our solar system (in volume) is often overlooked by astronomers, whose eyes are trained on the dramatic gas-giants Jupiter and Saturn. Only one mission has flown by Uranus–Voyager II, which captured the following undramatic photo in 1986 as it whipped through on its way to Neptune.
All of this is a shame, Uranus is not only the first ice-giant planet but it is unique in the solar system for rotating vertically rather than horizontally (probably thanks to some apocalyptic super collision long ago in the planet’s history). From our perspective, the moons of Uranus orbit around it like a clock’s hands and its sporty red rings sometimes give it the appearance of a target. Uranus has an incredibly long rotation around the sun. One Uranus year equals 84 Earth years. Because it spins vertically rather than horizontally, one pole is cast in a super winter which lasts twenty of our earth years (remember the poles of Uranus are on the equator). Voyager flew by during the deep freeze of winter to get that boring photo up there, but now the seasons are changing and spring is coming to Uranus’ northern pole while fall is coming to the south (I wish there were a different name for the side poles—this is really confusing to write about).
Because of the seasonal change, huge storms (the size of a continent on Earth) are tearing through the Uranian atmosphere with 500 kilometer-per-hour methane winds. Keep in mind that Uranus has the coldest atmosphere in the solar system, probably because the collision which knocked it on its side dissipated its primordial heat (although nobody really knows). Temperatures there get down to a chilly –224 °C. Brrr!
The spring storms are apparently dramatic and fierce enough to be seen from Earth. Yesterday astronomers reported the appearance of a huge white speck with an albedo ten times that of the planet. This methane storm probably looks like an immense immense thundercloud spreading above the usually placid blue cloud cover of the ice world. Saturn has been going through its own cycle of super storms recently (in addition to the great hexagonal storm raging on its north pole). Its tempting to adapt the folksy mannerisms of country smalltalk and suggest that weather in the solar system has been bad lately–but humankind is probably only just now able to apprehend such phenomena!
Mimas is a moon of Saturn. Discovered late in the 18th century by the astonishing Sir William Herschel, Mimas is the smallest (known) astronomical body which is spherical from self-gravitation (here is an explanation of what that means). The moon’s most noteworthy feature is an enormous impact crater named Herschel which is 130 kilometres (81 mi) across–about the same as the distance between New York and Philadelphia. Wikipedia gives some additional dimensions of the crater:
Herschel’s diameter is almost a third of [Mimas’] diameter; its walls are approximately 5 kilometres (3.1 mi) high, parts of its floor measure 10 kilometres (6.2 mi) deep, and its central peak rises 6 kilometres (3.7 mi) above the crater floor.
If you were standing in the crater (which you should not do!) it would be a great broken plain surrounded by cliffs thirteen times taller than the Empire State Building. In the middle you could see a huge mountain slightly shorter than the tallest mountain in North America. Jagged craters and valleys as deep as Lake Baikal would lie around you.
A great series of impact cracks on the opposite side of the moon would seem to indicate that the collision which created Herschel nearly shattered Mimas (which is composed principally of ice).
The moon’s name might be of passing interest to followers of my Deities of the Underworld category. In Greek mythology, Mimas was one of the monstrous sons of Gaia. He was born with snakes for legs and he was clad in full armor. In the Aeneid, Virgil tells the story of how Hephaestus imprisoned Mimas under Vesuvius during Gaia’s great rebellion against the Olympian gods. As the imprisoned giant shakes so to does the area around the Bay of Naples.
As I was researching this article, I was struck by how many moons Saturn has! As a special bonus feature, here is an alphabetic list of Saturn’s named moons (several more remain anonymous): Aegaeon, Aegir, Albiorix, Anthe, Atlas, Bebhionn, Bergelmir, Bestla, Calypso, Daphnis, Dione, Enceladus, Epimetheus, Erriapus, Farbauti, Fenrir, Fornjot, Greip, Hati, Helene, Hyperion, Hyrrokkin, Iapetus, Ijiraq, Janus, Jarnsaxa, Kari, Kiviuq, Loge, Methone, Mimas, Mundilfari, Narvi, Paaliaq, Pallene, Pan, Pandora, Phoebe, Polydeuces, Prometheus, Rhea, Siarnaq, Skadi, Skoll, Surtur, Suttung, Tarqeq, Tarvos, Telesto, Tethys, Thrym, Titan and Ymir.