Timeline of knowledge about the interstellar and intergalactic medium
The interstellar and intergalactic medium (ISM and IGM) is the matter that exists between stars, galaxies, and other objects in space. Thousands of years ago, people didn't know about the interstellar and intergalactic medium. They only knew about the stars and galaxies they could see in the night sky.
In the 1600s, people began to think that there was something in between the stars, but it wasn't until the 1900s that scientists were able to prove it. In the 1920s, the first evidence of gas clouds outside of the Milky Way galaxy was discovered.
In the 1950s, astronomers were able to measure the temperature in between galaxies for the first time. They found that it was much colder than they expected, only a few degrees above absolute zero. This was an important discovery because it meant that interstellar gas was not just empty space—it had to be made up of small particles and dust.
In the 1960s, NASA launched the first space probe to look at interstellar and intergalactic matter. Soon after that, the Hubble space telescope started to observe the far reaches of the universe, providing scientists with a much clearer picture of what was out there.
Now, astronomers have a pretty good understanding of the interstellar and intergalactic medium. They know that it is filled with gas, dust, and other particles, and that it contains more energy than the stars and galaxies do. They also know that it is made up of a variety of elements, including hydrogen, helium, and other heavier elements. Scientists are still learning new things about the ISM and IGM every day.
In the 1600s, people began to think that there was something in between the stars, but it wasn't until the 1900s that scientists were able to prove it. In the 1920s, the first evidence of gas clouds outside of the Milky Way galaxy was discovered.
In the 1950s, astronomers were able to measure the temperature in between galaxies for the first time. They found that it was much colder than they expected, only a few degrees above absolute zero. This was an important discovery because it meant that interstellar gas was not just empty space—it had to be made up of small particles and dust.
In the 1960s, NASA launched the first space probe to look at interstellar and intergalactic matter. Soon after that, the Hubble space telescope started to observe the far reaches of the universe, providing scientists with a much clearer picture of what was out there.
Now, astronomers have a pretty good understanding of the interstellar and intergalactic medium. They know that it is filled with gas, dust, and other particles, and that it contains more energy than the stars and galaxies do. They also know that it is made up of a variety of elements, including hydrogen, helium, and other heavier elements. Scientists are still learning new things about the ISM and IGM every day.