The supernova that created what was now know as the Crab Nebula was observed by Chinese astronomers a thousand years ago. It's young age make the remnant nebula and the pulsar it left behind ideal for study.
Astonomers have found the the super massive black hole at the center of spiral galaxies is always about one percent of the mass of the galaxy's central bulge. They are now interested in determining if this the relationship applies to globular clusters, such as Messier 15, which resemble galactic bulges. In other words, are globular clusters tiny galaxies?
Messier 105 is a normal run of the mill elliptical galaxy which, along with it's nearby cousins, is surrounded by a huge ring of primordial hydrogen and apparently lacking in dark matter.
Messier 34 is one member of a group of nearby clusters of stars. It is classified as an open cluster because it formed rather recently and is too small for the star to stay together so they will gradually disperse.
The Tirangulum galaxy, Messier 33, is a spiral galaxy with no central bulge. Astonomers believe that such galaxies do not have a central super massive black hole and have absorbed few if any small galaxies.
Spiral Galaxy Messier 65 recently encountered another galaxy causing one of its spiral arms to partially disappear by falling into the galactic center.
The Messier 104 was the first 'nebula' Melvin Slipher examined to determine how fast it is moving. He found it is moving away far too fast to be part of the Milky Way.
In 1974 Human Kind used the Aracebo radio telescope to send a message to the Hercules globular cluster. With luck we'll hear and answer in about 50,000 years. But it's unlikely because globular clusters are not good place to live.
Unlike the fuzzy objects in Messier's catalog, Messier 40 is pair of stars that aren't even a binary. So does the object belong in the catalog? Well, that was Messier's decision.
The Eagle Nebula is on of the most beautiful objects in the sky (once you take a long exposure photograph of it). What is going on to make it so beautiful?
Messier 56 is little studied globular cluster because it's difficult to observe being close to the galactic plane and one of the most distant. But it is known to be one of the oldest globular clusters, nearly as old as the Milky Way.
Paul shares a photo of comet Garradd, that happened to be near Messier 92, to show how much they look alike and why comet hunter Charles Messier was so annoyed by these nebulae that he cataloged all those he saw.
Messier 77 is a Seyfert galaxy meaning it has an active galactic nucleus with a large cloud of hot gas being absorbed by the central super massive black hole. That places it between the Milky Way with a mostly dormant nucleus and a quasar with an extremely active nucleus.
M110 is a dwarf elliptical galaxy left over from the formation of M31 Andromeda galaxy which it now orbits. It is a late addition to the Messier catalog as Messier discovered it but didn't specifically catalog it.
Messiers 4 is a nearby globular cluster of very old stars many of which are white dwarfs. The dwarfs' were individually resolved by the Hubble Spce telescope and the oldest dated to about 12 billion years, consistent with the age of the universe.
The first ever measurement of the proper motion of the Andromeda galaxy confirmed it is heading for a collision with the Mily Way in about four billion years.
The Pinwheel galaxy, M101, is a jumble of spiral arms thought to be produced by stars formed by compression waves propagating around the galaxy. It is also the site of the most recent type 1a supernova.
The Pelieades is an open cluster of stars that is passing through a diffuse cloud and dust to create a reflection nebula visible in long exposure photographs. Although there are about a thousand stars in the cluster the seven brightest are easily visible with the naked eye for now as they will eventually explode as supernovae.
Astronomers recorded the positions of the stars in the open cluster Messier 35 for decades to track their motion and from that determine the mass of the cluster. Based on their measurement it does not contain much if any dark matter.
Galacy BX442 is a very old galaxy ten billion light years from earth. It resembles a grand design spiral galaxy but its spectra reveals it is far to turbulent. So the spiral structure is probably due to a passing or nearby companion galaxy.
The Owl nebula is a shell of gas cast off from a star when it evolved into a red giant. This nebula is oriented relative to Earth so the geometry of the gas release is apparent to astronomers.
Messier 32 is an unusually compact dwarf elliptical galaxy. Astronomers thing it was once a larger spiral galaxy that lost its disk of stars to the Andromeda Galaxy leaving only the core behind.
The central star of the planetary nebula Messier 76 is quite rare. It is a white dwarf with a surface layer of carbon rather than hydrogen or helium. Apparently after its first expansion phase when it release most of it's remaining hydrogen creating the nebula it contracted and experienced a helium flash converting the helium to carbon and created a second nebula.
The Andromeda Galaxy, Messier 31, shares the title of the largest galaxy in the Local Group with the Milky Way. It was key to astronomers' realization that the universe is larger than the Milky Way.
Lenticular galaxies, such as Messier 85, often look like elliptical galaxies to us but they are disk shaped rather than spherical like the ellipticals. They are common in galaxy clusters where spiral galaxies are rare and rare outside the clusters where spirals are common. So astronomers think they are formed when a spiral galaxy encounter the gas cloud of a cluster and has its dust and gas, and hence spiral arms, stripped from it.
The open cluster Messier 67 has been thoroughly studied because it looked liked the best candidate for the location where the star nearest and dearest to our hearts was formed; our sun Sol.
The ring nebula was once thought to be a sphere of matter discharged by its central star that was so thin that only the edges were visible. It is now thought to be truly ring shaped and oriented so we see through it from Earth.
Spiral galaxy Messiar 65 has been undisturbed in its recent history in contract to it's companion in the Leo Triplet, Messier 66, which has many regions of active star formation.
The traditional theory of globular clusters is that their stars all formed at roughly the same time so stars of the same mass should have the same properties. But a close look at the clusters' color magnitude diagrams reveals most have two, occasionally, three populations of stars likely formed hundreds of millions of years apart. Spectra of certain elements in the stars reinforce the presence of multiple stellar populations.
The Large and small Mangellanic clouds are dwarf galaxies that orbit the the Milky Way and possibly each other as well. They are rather close to the Milky Way at present in their highly eccentric orbits.
The Wild Duck is an open cluster of just the right age with the right size stars so there are several Delta Scuti stars undergoing the kappa mechanism making them pulsate and vary in brightness.
