Top 10 Most Important Discoveries in Astronomy


Astronomy is the cool, sexy field of the scientific world. Sure, biologists and chemists are out there curing diseases or whatever, but they’re just so boring. Meanwhile, astronomers are busy showing us sweet pictures of distant planets and playing around with telescopes the size of buildings. How can you compete with that? You can’t, so here are the ten most important things astronomers throughout the ages have discovered:

10. The Movement of the Stars and Planets


The Discovery

It’s tough to wade through a couple thousand years of ancient Babylonian, Egyptian, Greek, Indian, Chinese, Mayan and Persian astronomical history to pick out the highlights, so I’ going to cheat and roll all of their achievements up into one entry. Maybe if their civilisations hadn’t died out they would have got a better spot on this list, but because they couldn’t keep their empires together the ancient world gets stuck with the number ten spot. That’ll learn ‘em.

How Important Was It?

Many of their accomplishments form the basis of modern astronomy, but it’s the fact that they tracked the movement of the stars and planets that really got the whole ball rolling. The realisation that the stars in the sky follow fixed, predicable patterns, along with the discovery of planets that follow their own paths, are the two most basic, fundamental concepts of astronomy. And also astrology, an equally important field of study.

9. The Heliocentric Model


The Discovery

Astronomers had speculated about heliocentrism (the idea that the Earth revolves around the sun, not the other way around) since ancient times, but in 1543 Copernicus was the first person to actually demonstrate the math behind the idea to prove it was a viable concept.

How Important Was It?

It took a while for Copernicus’ model to become universally accepted. (Get it? Astronomy puns are so easy.) Once it finally took hold it formed the basis of a scientific revolution. It eliminated many of the problems caused by the old geocentric model (it’s tough to make accurate calculations if you think the Earth isn’t moving), making it the first major shift in the field of astronomy since people realised the sun was a star and not an angry God. Also, his discovery made us feel stupid for once thinking we were the centre of the universe. Thanks a lot, Copernicus.

8. Kepler’s Laws


The Discovery

In 1609, a German astronomer named Johannes Kepler told the world that planets moved around the sun on elliptical routes, not in perfect circles as was commonly believed. Yeah, you know science can be boring when ellipses instead of circles is one of its most important discoveries.

How Important Was It?

Elliptical movement means that the distance between the sun and any given planet changes over time, and that’s an important thing to recognise if you want to figure out how far away a planet is and how fast it’s moving (the closer it is to the sun, the faster it moves). Thanks to Kepler’s laws, astronomers were able to predict the motion of the planets with far greater accuracy than before.

7. The Moons of Jupiter


The Discovery

Galileo, arguably the most important scientist ever, used a fancy telescope he half invented and half stole the idea for to discover four moons orbiting Jupiter in 1610. They were the first moons of another planet to be spotted, making them a landmark discovery. More importantly, we recently discovered that The Moons of Jupiter would make a sweet band name.

How Important Was It?

Remember when we said it took a while for heliocentrism to be accepted? Galileo’s discovery was the most important piece of evidence presented in support of Copernicus’ theory—the moons offered undeniable proof of celestial bodies that orbited something other than Earth. They also proved that planets other than Earth had moons, just in case it wasn’t already clear that we’re not special.

6. Herschel’s Map


The Discovery

From 1780 to 1834, telescope maker William Herschel and his sister Caroline systematically mapped the heavens, charting thousands of stars and nebulae in the process. He also discovered Uranus, and if astronomers had stuck with his proposed name of Georgium Sidus (George’s Star) we would have been saved centuries of terrible jokes.

How Important Was It?

Making a map barely counts as a discovery; yet Herschel’s was extremely important, because when it was all finished it revealed the shape and size of the Milky Way galaxy. Not only was it much, much larger than had previously been estimated, but it turned out to be disc shaped, and our own sun was located nowhere near the centre. Herschel’s work cleared up a lot of misconceptions about our own little corner of the universe.

5. The Theory of Relativity


The Discovery

Albert Einstein, a German scientist you may have heard of, proposed his theory of relativity in 1915. Summed up, the theory states that mass can warp both space and time, which allows large masses like stars to bend light. It’s trippy stuff.

How Important Was It?

To understand the true significance of relativity you’d need to listen to someone who has a deeper knowledge of physics than some guy who writes lists for the Internet. Put as simply as possible, relativity replaced Newton’s theory of mechanics, which had been the basis of astronomy for the previous 200 years. Einstein argued that motion was relative, and that the concept of time depended on velocity. This new way of thinking was used to explain various astronomical problems that had been impossible to solve using Newton’s old-timey methods, and gave astronomers new ways of theorising about how the universe worked.

4. The Expanding Universe


The Discovery

Edwin Hubble gave the astronomy world a one-two punch of knowledge between 1924 and 1929. Not only was he the first to discover other galaxies, but by tracking their movement he learned that they are moving away from us (and the ones farther away are moving faster), which was the first evidence we had to suggest that the universe is expanding.

How Important Was It?

Hubble’s first discovery changed our conception of the size of the universe. It was the first proof we had that space was really, really, really big. His second discovery offered major support for the Big Bang theory, which is the best idea we’ve got as to how the universe was born. See, that’s the kind of stuff that gets a giant space telescope named after you.

3. Radio Astronomy


The Discovery

Remember when radio was all the rage in the entertainment world? Of course you don’t, you’re not 80 years old. But in the world of astronomy radio is still important today, thanks to a discovery by Karl Jansky in 1931. His experiments with radio waves led him to find signals coming from the centre of the galaxy, and he’s considered the founding father of radio astronomy as a result.

How Important Was It?

Scientists that followed up on Jansky’s discovery found that there are all sorts of radio waves coming at us from space, and the sources of most of them are celestial objects that can’t be seen with other methods. Radio astronomy soon turned into a huge field that’s been responsible for the discovery of many stars and galaxies, as well as brand new classes of objects like quasars and pulsars. I don’t really know what those are, but they sound badass so this discovery must be important.

2. Cosmic Microwave Background Radiation


The Discovery

It was a pair of radio astronomers, Arno Penzias and Robert Wilson, who discovered cosmic microwave background radiation in 1964. CMBR is a type of radiation that’s present in very small quantities (hence the term background) all throughout space, and is believed to be leftover from when the universe was in a very early stage of growth.

How Important Was It?

CMBR offered further evidence in support of the Big Bang theory. The idea is that this radiation has been present since the Big Bang, and has spread out as the universe expands (see number four on the list). Its discovery was enough to turn the idea of the Big Bang from a contested concept into the predominant explanation of our origins. Penzias and Wilson won the Nobel Prize for their work; and we all know nobody ever gets a Nobel Prize unless they’ve really earned it.

1. Extrasolar Planets

extra solar planets

The Discovery

An extrasolar planet is one that’s outside of our solar system, and astronomers believed in their existence for a long, long time. Yet, it wasn’t until recently that the tools to actually spot one became available; it was only in 1995 when Swiss astronomers Didier Queloz and Michel Mayor discovered a planet in the constellation Pegasus they dubbed 51 Pegasi b. Yeah, astronomers may be great at discovering things but they’re not great at naming them.

How Important Was It?

Not only did Queloz and Mayor finally prove that extrasolar planets are out there, but the method they used has been repeated to find many more. Nearly 500 extrasolar planets are now known to exist, and that’s just the beginning (right now astronomers can only spot ones that are massive). As more and more planets are found, it’s only a matter of time until the most important astronomical discovery in history is made: a planet full of benevolent and sexy aliens. Hurry it up, science!

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  1. Astronomy now a very simple way to settle Hubble’s Constant, by inputting to an equation, the numerical value of Pi and the speed of light (C) from Maxwell’s equations, and the value of a parsec. NO space probe measurements (with their inevitable small measuring / interpretation errors) are now required. Hubble’s Constant is ‘fixed’ at 70.98047 PRECISELY. This maths method removes the errors / tolerances that is always a part of attempting to measuring something as ‘elusive’ as Hubble’s Constant. This has very deep implications for theoretical cosmology. If this is not accepted, you will never be able to ‘escape’ today’s ‘Hubble mess’, and endless guessing and bickering over something purely universe maths that’s now very easy to settle. NASA will never solve this by measuring. Look at their latest confused ‘guesses’, and the Hubble conflicts on Wikipedia. I rest this case. ‘The equation to perform this is 2 X a meg parsec X light speed (C). This total is then divided by Pi to the power of 21. This gives 70.98047 kilometres per sec per meg parsec. The equation to perform this can also be found in ‘The Principle of Astrogeometry’ on Amazon Kindle Books. This also explains how the Hubble 70.98047 ‘fixing’ equation was found. David


    After reading this topic I came to think about space once more. This page is indeed an extraordinary page on astrophysics. I also read the above comments of different readersand want to say them, that we cannot expect everything in one page,also don’t put God in between the science. They both are indeed a different scope.yeah one thing I think should also be included is about black hole and dark enegry as they are the latest scope of astrophysics and are sure to change our thoughts of astrophysics. But as the whole I liked the page.

  3. I would like to see more people include Indigenous Australians as the first people to track the stars and realise the importance of them in relation to seasons etc.

  4. just wanted to put it out there that the information about the theory of relativity is incorrect. mass cannot warp time & space. relativity is all about how the speed of light is the only constant thing in our universe and as a result of this, other things in our universe like time, space and mass constantly change depending on relativistic speeds. also, it does not allow planets to bend light.

  5. John Dinsdale on

    It has to be the discovery that Planets are very common. If only we could see one closeup.
    Oh, and Dark Matter. Strange that.

  6. I would get rid of Herschel’s map and replace it with Hubble’s discovery that the “spiral nebulae” were, in fact, other galaxies. I would also argue that Relativity, Kepler’s Laws, and the Heliocentric theory are not astronomy discoveries per se, and could be replaced with:

    1. Discovery of increasingly-expanding universe
    2. Dark Matter
    3. Voids (like the Bootes Void)

  7. ankush bansal on

    i think that black holes is the most important topic of astronomy.i think if we came to about the center of black will anwser that there is many many universe and it is a process which will go on till the(sorry that i can’t tell)i also think ‘if we able find any alien on any planet’ it means that there is no god’

    • Just because there may possibly be life elsewhere in the vastness of space does not mean that a “God” cannot exist. Perhaps not in the way we have been taught and view as today as a supernatural being. Interestingly enough, when you look at the “map” of the universe, and the congregations of galaxies. They come to form webs and a structure similar to a sponge. Maybe not in the overall structure from a far, but when viewed closely they do resemble that of the neurons in our brains. Based on Einstein’s theories of energy transfer, and that it cannot be created or destroyed, only transferred. That scientists have measured that after a human dies, a noticeable weight ( I think around 2lb) leaves the body from the loss of energy, it must go somewhere to serve another purpose.

      It is just too early, and to blindly to say that a God may or may not exist. Even if life is found elsewhere. And like most per-conceptualized theories, all of our own now, might very well be wrong, or off track in the future once proven.

      Don’t mean to troll the old post, but all religions of all kinds have lead humanity as a whole to finding and later proving past theories as fact. While trying to describe them in their own terms of their own times.

      • Also on the black holes, scientists are leading to believe that every second about, a new black hole is formed in our universe. It is not necessarily the rapid formations of the black holes we have to worry about, as they do collide and dissipate. It is the dark energy (not to be confused with dark matter) that is always trying to push matter apart. Where in trillions– of years, may lead to us not being able to see any stars at all due to their increased distance from ours. Of course by that time, or soon before it we will also have the collision of the Andromeda Galaxy which could fling us off into space, or place us in the center of the newly formed galaxy. Though chances of utmost destruction or slim to nil, so no sweating there. Grab a beach chair and enjoy the show!

  8. but i think the universes don’t expanding and we just turn around some thing and change place not expand.

  9. These twn most important discoveries are what makes up our modern understanding of the stars and planets,


    just wait, watch and see many more important discoveries are going to come within the next few decades

  10. i think probably in the future the discovery of dark matter will prove to be the most important