Article written by: Heather Alexander

Have you ever had a fun night out with friends, or a lazy day in with loved ones, or even just strolled down the street, and asked the question “Who discovered…?”

I am the type of person who asks this question, frequently. Thanks goodness I have Google simply a touch away on my phone. If Google were to ever get fed up with a person asking questions, it would be me! I thought I would turn this frequently asked question of mine into an article. When you work in a Planetarium, or any science industry at all really, you get asked this question numerous times throughout your day. So here are some of my top “Who discovered…?” questions and the answers to them.

Portrait of Sir Isaac Newton. Credit: Wiki Commons, public domain image


Who discovered gravity?

This is a question a lot of people ask, but then realise that they already knew the answer. The person who discovered gravity was Sir Isaac Newton in 1687. He is a household name for sure, and quite rightly. He was a genius of gigantic proportions. He was born prematurely on 25th December 1642, and wasn’t expected to survive the night. He grew into a man with a flair for mathematics and physics.

The most common story that we learn from an early age is that Newton discovered gravity when he was sitting under an apple tree, and an apple fell, hit his head, and gave him the idea. This is not really what happened, in fact it’s more of an anecdote. No one is entirely sure of the exact truth of how Newton discovered gravity, but all accounts involve an apple. An English clergyman wrote how he and Newton were sipping tea in the garden while he was visiting and as an apple fell Newton posed the question “Why should the apple always descend perpendicularly to the ground?” Another colleague of Newton’s claimed that Newton got the idea when travelling to see his mother.

The Red Planet, named after the Roman God of War: Credit: NASA


Who discovered Mars?

Mars is one of the visible planets in the night sky (along with Mercury, Venus, Jupiter and Saturn).  Due to this fact is hard to say who really did discover Mars first, as people have been able to see it for millennia.

The answer you will get on Google is that it was Christian Huygens in 1659, but again you have to remember he didn’t discover the planet for the very first time as we’d already been able to see it. The Dutch astronomer drew Mars with the observations he made using a telescope he designed himself. He also discovered a strange feature on the planet that became known as Syrtis Major. Before this Nicolas Copernicus was the first astronomer to hypothesise that Mars and a few other bodies known at the time were planets. Tycho Brahe, a Danish astronomer made accurate calculations of the position of Mars as early as 1576. Johannes Kepler theorized that the orbit of Mars was elliptical in contradiction to what astronomers believed at the time.

So in answer to the actual question, it’s hard to say, but there have been many famous astronomers invested in Mars and have helped it to become the planet that we know today.

Image of Sirius_A_and_B

An artist’s impression showing how the binary star system of Sirius A and its diminutive white dwarf companion, Sirius B, might appear to interstellar travellers. Credit: NASA, ESA, G. Bacon (STScI)


Who discovered the brightest star in the sky?

Sirius, also known as the Dog Star, was a star well known to the ancient people, so again it is hard to state who first discovered it. When it comes to this particular star it is important to look at who was making significant observations regarding it.

In 1718, Edmond Halley was studying Sirius along with a few other stars and discovered that stars have “proper motion” relative to one another.

In 1862, Alvan Graham Clark made a huge discovery whilst observing Sirius. He was to find that it had a faint companion, which is now known as Sirius B and we now know is a “white dwarf”, an exotic state of matter that our Sun will end its day in, some 5 billion years from now.


The first proper image was Pluto was first taken in July 2015. Credit: NASA


Who discovered Pluto?

Another commonly asked question. This one is a little simpler to answer. In 1930, an astronomer named Clyde Tombaugh discovered the planet Pluto (at the time it was known as a planet).

At this time astronomers had noticed that there seemed to be issues with the orbits of the planets Uranus and Neptune, and they theorised that another planet must be asserting its influence. At the Lowell Observatory in 1929, Tombaugh joined the mission to find the missing planet. On Feb. 18, 1930, Tombaugh noticed movement across the field of a pair of images taken a month beforehand. After studying the object to confirm it, the staff of Lowell Observatory officially announced the discovery of a ninth planet on March 13.


Image taken of Halley’s Comet in 1986. Credit: NASA


Who discovered Halley’s Comet?

Unequivocally the most famous comet we have ever discovered. Throughout history there have been recordings of this famous periodic comet. It wasn’t until Edmond Halley started to examine reports of a comet approaching the Earth in 1531, 1607 and 1682, that he decided it must be the same comet. It seemed to return every 75 years and he made the prediction that the comet would return in 1758.

Unfortunately Halley didn’t live long enough to see the comet return to the Earth, but his discovery led to the comet being named after him, and rightly so!

We last got to see Halley’s Comet in 1986, and won’t see it again until 2061.


Image showing the potential size of a solar flare in comparison to the Earth. Credit: NASA/SDO/Steele Hill)


Who discovered solar flares?

Our sun has always fascinated us. It was Richard Christopher Carrington (and independently by Richard Hodgson) who first observed solar flares on the Sun as localized visible brightening’s of small areas within a sunspot group.

A solar flare is a sudden flash of increased Sun’s brightness, usually observed near its surface. Flares are often, but not always, accompanied by a coronal mass ejection. To read more about solar flare and coronal mass ejections, check out the solar storm of 1859.


A Diagram showing the distance of the Oort Cloud from the Sun. The Oort Cloud is estimated to be between 5,000 and 50-100,000 AU away. Credit NASA


Who discovered the Oort Cloud?

The Oort cloud is a swarm of comets that basically encircle our solar system, extending from beyond the orbits of Neptune and Pluto out to 100,000 times the Earth-Sun distance, nearly one-third the distance to the nearest star.

Jan Hendrik Oort, a Dutch astronomer, was the first person to “discover” the cloud. The reason for the inverted comas on the word discovered, is because he made the discovery not through telescopic observations, but through a theoretical study of the orbits of long-period comets (these would have an orbit period greater than 200 years.) Long-period comets can have orbits ranging from eccentric ellipses to parabolas. While trying to explain the distribution of these orbits, Oort concluded that the only explanation was that the source of these comets had to be a massive cloud of comets surrounding the solar system.