1 00:00:00,120 --> 00:00:01,920 Speaker 1: This Day in History Class is a production of I 2 00:00:02,040 --> 00:00:07,040 Speaker 1: Heart Radio. Hey everyone, if I sound a lot cozier today, 3 00:00:07,160 --> 00:00:09,920 Speaker 1: it's because I am. I'm at home for the holidays. 4 00:00:10,240 --> 00:00:13,720 Speaker 1: But this is this Day in History class, which means 5 00:00:13,880 --> 00:00:16,680 Speaker 1: you'll still get a new slice of history every day. 6 00:00:16,720 --> 00:00:20,639 Speaker 1: So let's get on with the show. Today is December. 7 00:00:29,400 --> 00:00:35,800 Speaker 1: The day was December n American astronomer Edwin Hubble announced 8 00:00:35,840 --> 00:00:40,200 Speaker 1: the existence of galaxies beyond the Milky Way. Hubble graduated 9 00:00:40,200 --> 00:00:42,920 Speaker 1: from the University of Chicago in nineteen ten with the 10 00:00:42,960 --> 00:00:46,720 Speaker 1: Bachelor of Science in Mathematics and astronomy, and in nineteen 11 00:00:46,800 --> 00:00:49,920 Speaker 1: fourteen he went back to the University of Chicago to 12 00:00:49,960 --> 00:00:53,760 Speaker 1: get his doctorate in astronomy. There he began working at 13 00:00:53,800 --> 00:00:58,000 Speaker 1: the Yerkes Observatory, where he studied nebulie or anything that 14 00:00:58,040 --> 00:01:02,360 Speaker 1: wasn't immediately identifiable as this are. He got his doctorate 15 00:01:02,360 --> 00:01:06,080 Speaker 1: in nineteen seventeen, but that same year the US entered 16 00:01:06,120 --> 00:01:10,160 Speaker 1: World War One, and Hubble joined the army. Once the 17 00:01:10,160 --> 00:01:14,640 Speaker 1: war ended, he returned to astronomy. Astronomer George Hale, founder 18 00:01:14,680 --> 00:01:19,000 Speaker 1: of the Yerkes Observatory and director of the Mount Wilson Observatory, 19 00:01:19,120 --> 00:01:22,240 Speaker 1: had offered Hubble a job at Mount Wilson before he 20 00:01:22,280 --> 00:01:26,160 Speaker 1: went off to war. In nineteen nineteen, Hubble took a 21 00:01:26,200 --> 00:01:31,360 Speaker 1: staff position at Mount Wilson Observatory near Pasadena, California. There 22 00:01:31,440 --> 00:01:34,960 Speaker 1: he worked with a one hooker telescope, which was then 23 00:01:35,200 --> 00:01:38,959 Speaker 1: the largest in the world. He stayed at the observatory 24 00:01:39,040 --> 00:01:44,360 Speaker 1: for his whole career. At Mount Wilson, Hubble continued studying nebulae. 25 00:01:44,920 --> 00:01:48,080 Speaker 1: At this time, scientists thought the Milky Way made up 26 00:01:48,080 --> 00:01:51,680 Speaker 1: the entire universe. In spiral nebulae were thought to be 27 00:01:51,760 --> 00:01:55,720 Speaker 1: clouds of gas or dust within the Milky Way, but 28 00:01:55,800 --> 00:02:00,640 Speaker 1: in nineteen twelve, astronomer Henrietta Levitt showed how to use sefid's, 29 00:02:00,880 --> 00:02:04,760 Speaker 1: or stars that brightened and dem periodically, to estimate their 30 00:02:04,800 --> 00:02:09,000 Speaker 1: distance from Earth, and some astronomers did believe that the 31 00:02:09,040 --> 00:02:12,760 Speaker 1: nebulae were distant island universes that were separate from the 32 00:02:12,800 --> 00:02:18,040 Speaker 1: Milky Way. Starting in nineteen twenty three, Hubble identified Sefid 33 00:02:18,240 --> 00:02:22,160 Speaker 1: variable stars and what was then known as the Andromeda nebula. 34 00:02:22,760 --> 00:02:26,880 Speaker 1: Based on their brightness, luminosity, and the distances of sefiad 35 00:02:26,960 --> 00:02:30,240 Speaker 1: stars in the Milky Way. Hubble determined that the stars 36 00:02:30,280 --> 00:02:34,160 Speaker 1: were at least eight hundred thousand light years away. That 37 00:02:34,200 --> 00:02:37,200 Speaker 1: meant that they were beyond the boundaries of the Milky Way, 38 00:02:37,280 --> 00:02:40,640 Speaker 1: which had a maximum diameter of about one hundred thousand 39 00:02:40,760 --> 00:02:45,360 Speaker 1: light years. This discovery also revealed that nebulae are different 40 00:02:45,440 --> 00:02:49,040 Speaker 1: star systems, and that the universe extends past the reaches 41 00:02:49,080 --> 00:02:53,800 Speaker 1: of the Milky Way. He called these galaxies extra galactic nebulae. 42 00:02:54,840 --> 00:02:58,400 Speaker 1: By the end of nineteen other astronomers were aware of 43 00:02:58,440 --> 00:03:04,000 Speaker 1: Hubble's findings. On December nine, four, he published his observations 44 00:03:04,040 --> 00:03:07,679 Speaker 1: for review at a meeting of the American Astronomical Society 45 00:03:07,960 --> 00:03:12,040 Speaker 1: that would take place two days later. Other astronomers accepted 46 00:03:12,080 --> 00:03:16,520 Speaker 1: Hubble's conclusions pretty quickly. Hubble went on to find and 47 00:03:16,600 --> 00:03:20,880 Speaker 1: describe more galaxies, dividing them into the categories of regular 48 00:03:21,080 --> 00:03:25,080 Speaker 1: or irregular, and the regular ones as spiral or elliptical 49 00:03:25,240 --> 00:03:28,919 Speaker 1: based on their shape, and he made many other significant 50 00:03:28,919 --> 00:03:34,160 Speaker 1: contributions to cosmology. In Hubble combined his work with that 51 00:03:34,240 --> 00:03:38,960 Speaker 1: of astronomer Vesto Slifer and his assistant Milton Hamison, and 52 00:03:39,000 --> 00:03:42,880 Speaker 1: he found an essentially linear relationship between the distances of 53 00:03:42,920 --> 00:03:47,680 Speaker 1: galaxies and their radial velocities. That concept came to be 54 00:03:47,760 --> 00:03:51,520 Speaker 1: known as Hubble's law. Put simply, it says that the 55 00:03:51,600 --> 00:03:55,000 Speaker 1: farther apart galaxies are, the faster they move away from 56 00:03:55,000 --> 00:03:58,720 Speaker 1: each other. Hubble's findings helped lead to the notion of 57 00:03:58,760 --> 00:04:04,040 Speaker 1: the expanding universe. His work had big implications Due in 58 00:04:04,160 --> 00:04:08,080 Speaker 1: part to his observations, Debate intensified around the idea of 59 00:04:08,120 --> 00:04:13,040 Speaker 1: the Big Bang or the universe's earliest expansion. Some said 60 00:04:13,080 --> 00:04:16,200 Speaker 1: that the universe expanded from a single point at its origin, 61 00:04:16,680 --> 00:04:20,200 Speaker 1: while others said that the universe exists in a steady state. 62 00:04:21,279 --> 00:04:27,039 Speaker 1: The Hubble Space telescope, launched by NASA, is named after him. 63 00:04:27,080 --> 00:04:29,440 Speaker 1: I'm Eves Jeff Coote and hopefully you know a little 64 00:04:29,480 --> 00:04:33,240 Speaker 1: more about history today than you did yesterday. If you 65 00:04:33,240 --> 00:04:35,360 Speaker 1: want to hit us up on social media, you can 66 00:04:35,400 --> 00:04:39,600 Speaker 1: do so at t d I h C Podcast or 67 00:04:39,800 --> 00:04:42,800 Speaker 1: you can just email us at this Day at I 68 00:04:42,920 --> 00:04:46,680 Speaker 1: heeart media dot com. Thanks again for listening, and we'll 69 00:04:46,680 --> 00:04:52,440 Speaker 1: see you tomorrow. For more podcasts from my Heart Radio, 70 00:04:52,560 --> 00:04:55,120 Speaker 1: vis the I Heart Radio app, Apple Podcasts, or wherever 71 00:04:55,160 --> 00:04:56,440 Speaker 1: you listen to your favorite shows.