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Call me Pebbles
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This date is rather momentous because, 91 years ago, on this date Edwin Hubble announced that the physical universe in which we live is much, much bigger than we thought—there are other galaxies out there. In this day and age, after all the advancements in astrophysics and cosmology over the 9 decades hence, this doesn’t seem that big of a deal. However, prior to this announcement, we believed that the extent of the known universe lay neatly contained within our galactic fence line.
About 12 years prior in 1912, Henrietta Leavitt at Harvard computationalist discovered that a certain type of variable-brightness star, later named Cepheid variable stars after the first one discovered delta-Cephei (fourth brightest star in the constellation Cepheus), exists in which the period of variability, or the time between maximum and minimum brightness, is directly relatable to the absolute magnitude or luminosity. It was determined that by measuring the star’s apparent magnitude (how bright it appears to us on Earth) and using parallax to measure the distance to the star, we could then calculate the absolute magnitude. Working this backward, if we know a star’s absolute magnitude, we could then determine how far away it is by measuring its apparent magnitude.
When Hubble started observing stars, and ultimately Cepheid variables, in what was then called the Andromeda nebula, he calculated the distance to those Cepheid variables. With the radius of the Milky Way galaxy at a well-known 50,000 light years, Hubble quickly came to the conclusion that those variable stars were not within our own galaxy at distance beyond 1 million light years. Soon after, more and more measurements of distances to other “nebulae” were made. Thereafter, it was resolved that these “nebulae” were in fact other galaxies.
Call me Pebbles
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Where's Mah Reachin' Stick?
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This date is rather momentous because, 91 years ago, on this date Edwin Hubble announced that the physical universe in which we live is much, much bigger than we thought—there are other galaxies out there. In this day and age, after all the advancements in astrophysics and cosmology over the 9 decades hence, this doesn’t seem that big of a deal. However, prior to this announcement, we believed that the extent of the known universe lay neatly contained within our galactic fence line.
About 12 years prior in 1912, Henrietta Leavitt at Harvard computationalist discovered that a certain type of variable-brightness star, later named Cepheid variable stars after the first one discovered delta-Cephei (fourth brightest star in the constellation Cepheus), exists in which the period of variability, or the time between maximum and minimum brightness, is directly relatable to the absolute magnitude or luminosity. It was determined that by measuring the star’s apparent magnitude (how bright it appears to us on Earth) and using parallax to measure the distance to the star, we could then calculate the absolute magnitude. Working this backward, if we know a star’s absolute magnitude, we could then determine how far away it is by measuring its apparent magnitude.
When Hubble started observing stars, and ultimately Cepheid variables, in what was then called the Andromeda nebula, he calculated the distance to those Cepheid variables. With the radius of the Milky Way galaxy at a well-known 50,000 light years, Hubble quickly came to the conclusion that those variable stars were not within our own galaxy at distance beyond 1 million light years. Soon after, more and more measurements of distances to other “nebulae” were made. Thereafter, it was resolved that these “nebulae” were in fact other galaxies.
About 12 years prior in 1912, Henrietta Leavitt at Harvard computationalist discovered that a certain type of variable-brightness star, later named Cepheid variable stars after the first one discovered delta-Cephei (fourth brightest star in the constellation Cepheus), exists in which the period of variability, or the time between maximum and minimum brightness, is directly relatable to the absolute magnitude or luminosity. It was determined that by measuring the star’s apparent magnitude (how bright it appears to us on Earth) and using parallax to measure the distance to the star, we could then calculate the absolute magnitude. Working this backward, if we know a star’s absolute magnitude, we could then determine how far away it is by measuring its apparent magnitude.
When Hubble started observing stars, and ultimately Cepheid variables, in what was then called the Andromeda nebula, he calculated the distance to those Cepheid variables. With the radius of the Milky Way galaxy at a well-known 50,000 light years, Hubble quickly came to the conclusion that those variable stars were not within our own galaxy at distance beyond 1 million light years. Soon after, more and more measurements of distances to other “nebulae” were made. Thereafter, it was resolved that these “nebulae” were in fact other galaxies.
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Zeroth law of contact sports: If you don't want to get hurt, don't play. Got two concussions and tendinitis in my thumbs so I stopped playing hockey. Pardon the pun, but it really is a no-brainer.
This date is rather momentous because, 91 years ago, on this date Edwin Hubble announced that the physical universe in which we live is much, much bigger than we thought—there are other galaxies out there. In this day and age, after all the advancements in astrophysics and cosmology over the 9 decades hence, this doesn’t seem that big of a deal. However, prior to this announcement, we believed that the extent of the known universe lay neatly contained within our galactic fence line.
About 12 years prior in 1912, Henrietta Leavitt at Harvard computationalist discovered that a certain type of variable-brightness star, later named Cepheid variable stars after the first one discovered delta-Cephei (fourth brightest star in the constellation Cepheus), exists in which the period of variability, or the time between maximum and minimum brightness, is directly relatable to the absolute magnitude or luminosity. It was determined that by measuring the star’s apparent magnitude (how bright it appears to us on Earth) and using parallax to measure the distance to the star, we could then calculate the absolute magnitude. Working this backward, if we know a star’s absolute magnitude, we could then determine how far away it is by measuring its apparent magnitude.
When Hubble started observing stars, and ultimately Cepheid variables, in what was then called the Andromeda nebula, he calculated the distance to those Cepheid variables. With the radius of the Milky Way galaxy at a well-known 50,000 light years, Hubble quickly came to the conclusion that those variable stars were not within our own galaxy at distance beyond 1 million light years. Soon after, more and more measurements of distances to other “nebulae” were made. Thereafter, it was resolved that these “nebulae” were in fact other galaxies.
This date is rather momentous because, 91 years ago, on this date Edwin Hubble announced that the physical universe in which we live is much, much bigger than we thought—there are other galaxies out there. In this day and age, after all the advancements in astrophysics and cosmology over the 9 decades hence, this doesn’t seem that big of a deal. However, prior to this announcement, we believed that the extent of the known universe lay neatly contained within our galactic fence line.
About 12 years prior in 1912, Henrietta Leavitt at Harvard computationalist discovered that a certain type of variable-brightness star, later named Cepheid variable stars after the first one discovered delta-Cephei (fourth brightest star in the constellation Cepheus), exists in which the period of variability, or the time between maximum and minimum brightness, is directly relatable to the absolute magnitude or luminosity. It was determined that by measuring the star’s apparent magnitude (how bright it appears to us on Earth) and using parallax to measure the distance to the star, we could then calculate the absolute magnitude. Working this backward, if we know a star’s absolute magnitude, we could then determine how far away it is by measuring its apparent magnitude.
When Hubble started observing stars, and ultimately Cepheid variables, in what was then called the Andromeda nebula, he calculated the distance to those Cepheid variables. With the radius of the Milky Way galaxy at a well-known 50,000 light years, Hubble quickly came to the conclusion that those variable stars were not within our own galaxy at distance beyond 1 million light years. Soon after, more and more measurements of distances to other “nebulae” were made. Thereafter, it was resolved that these “nebulae” were in fact other galaxies.
Give Me All the Miatas
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Yes basically the distance away dictates how many years it would take for the light to reach Earth. Similarly it takes something like 8 minutes for the light from the Sun to reach the Earth.
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