Edmund Halley 1656-1742
Among his many studies are tides, magnetism, and trade winds. He cataloged 341 southern hemisphere stars and discovered a star cluster in Centaurus. He also made the first complete observation of a transit of Mercury on November 7, 1677. He also invented the diving bell. But his most famous accomplishment is that he worked out a theory of the orbits of comets, concluding that the comet of 1682 was periodic, and that it would return every 76 years. Halley had died by the time the comet returned so his whole life was pretty much totally wasted, but the success of the prediction greatly elevated the level of confidence people had in the horrible terrifying power of science. Even so, Americans never learned how to pronounce his name correctly.
Charles Messier 1730 - 1817
Chuck Messier was one comet-hunting sonuva bitch. He found a lot of comets but then he decided to catalog the location of many deepsky objects that could easily be mistaken for comets in small telescopes. At first he was annoyed by all the small fuzzy things that look like comets but later he began to realize that these were the real "who's who" of stuff to show the chicks with your telescope. His list contains a few more than 100 diffuse objects. The actual number is controversial because of problems with identifying certain objects. M40 may not exist at all, or at best is two stupid dim stars. Or maybe there was a wad of horse hair on his lens. Meanwhile M102 appears to be a duplicate entry of M101. That happens. Eventually he found out that you shouldn't call women "chicks" because babes hate that. Also, powdered wigs went out of style and never made a come back.
William Herschel 1738 - 1822
The discoveries Herschel made are many. He built a huge 48-inch telescope which was the world's largest for more than 50 years. He discovered what he first thought was a comet, but turned out to be a planet so that's a fail, but then he named it Uranus which is every fifth grader's favorite. Eventually he also discovered two moons orbiting Uranus; Titania and Oberon, and two moons of Saturn; Enceladus and Mimas. He determined that our solar system is moving in the direction of Hercules. In his spare time he cataloged about 2500 deep sky objects.
Caroline Herschel 1750 – 1848
Her brother Bill let her use the telescope pretty much anytime she wanted, If he didn't she would give him a wedgie. Like others of the time she assumed that the spiral thingies in the sky were just little dust bunnies or a place where the cosmic plumbing was stopped up or something. She drew a map of the Universe which looked like a cupcake that had the frosting licked off and then thrown into the street where it got ran over a few times. Our Sun was in the middle and the globular clusters were sprinkled around the edges. Most everyone agreed it was the best theory ever.
Henrietta Leavitt 1868 - 1921
Studying variable stars in the Magellanic Clouds, she discovered that certain variable stars have a cycle that corresponds to their luminosity; the brighter the star, the longer the period. Using this relationship, she was able to determine that the intrinsic brightness of these stars is predictable. By comparing that value to the apparent brightness, the difference can then be used to calculate their distance from Earth. This method revolutionized astronomy which perhaps is why they have never named any major telescopes after her.
Annie Jump Cannon 1863 – 1941
Information about the stars was coming in fast and furious now and someone needed to come up with a way to keep it all sorted and organized. Annie started the idea of classifying stars according to their surface temperatures by using the alphabet. The "A" stars as the hottest, then "B" for the next hottest, then "C" stars etc. But then someone noticed they forgot to carry the 2 or something so some of the cool stars were hotter than the hot stars. At first the men astronomers felt sorry for the women astronomers because the women back then were in charge of keeping track of this stuff on little cards with old-timey typewriters and the men had screwed it all up. But then Annie was like "Hey dorkamundos, everyone has problems. But not everyone is such a big baby about it. Who cares what hell they are called anyway? You don't hear the stars complaining like a bunch of dicks." So ever since then astronomy students have had to memorize that the stars from hottest to coolest are O B A F G K M and also it turned out that's really all the letters they needed. The conventional mnemonic is "Oh Boy Another Fine Girl Kiss Me" or if you prefer "Fine Guy Kissed Me" - don't ask don't tell, I don't need to know what you do on your own time.
Edwin Hubble 1889 - 1953
Before Hubble's big discovery many astronomers thought our Milky Way was the whole damn Universe. Even the spiral thingy in Andromeda was a mystery and usually referred to as "That Spiral Thingy in Andromeda." People had some vague ideas about such things but they were rather nebulous. A few folks had speculated wildly about "island universes" but Hubble found solid proof these galactic islands are all around us. He showed that these giant systems of stars are way outside of the Milky Way. He could have stopped there but then Hubble's wrote a law explaining how the galaxies are receding away from each other. This movement suggested the Universe is getting bigger, like a raisin pudding dough placed in an oven at 350 degrees for 45 minutes, which is pretty tasty so that was nice. But if the sky is getting bigger, that means it use to be smaller. Everyone freaked out when they realized this is true and they have never really gotten over it.
Albert Einstein 1879 - 1955
The contributions that Einstein gave to the astronomical community are so significant that the depth of some of them are still being explored today. Some of the areas of major impact concern the nature of light, gravity, time, and mustache growth.
It is in regards to the nature of light that Einstein received a Nobel Prize. He explained the "photoelectric effect." The essence of this effect is that when you put a spoon in a microwave oven and turn it on there will be lots of sparks and it will make black marks all over the inside of the oven. Einstein explained why this happens, way before microwave ovens were even invented.
Einstein gave us a whole new perspective on gravity called General Relativity. Instead of viewing gravity as an attractive force he viewed it as a stretched-out shape in the spacetime continuum, like when you put something with the density of a neutron star in a jock strap. By treating space and time as something with a shape that can be distorted in the vicinity of matter, he gave us a powerful tool for creating the opening graphics of sci-fi movies.