What we have Found and Learned
Astronomy is the most fascinating field of the scientific world. Using instruments the size of buildings, astronomers peer deep into the past as they study distant stars, planets and galaxies that are billions of years old.
For thousands of years ancient peoples observed the Sun, the Moon, the Visible Planets and the stars. Drawing on their religious and cultural traditions, they often explained what they saw in the heavens by weaving myth and filling the sky with both angry and benevolent gods as well as with places of white light that cuts across the black summer night sky – now known as a Milky Way galaxy – was the heavenly Nile River in the land of dead.
Until the last part of the eighteenth century, only six planets of the solar system was known – Mercury, Venus, Earth, Mars, Jupiter, and Saturn. Using steadily improving instruments, astronomers made increasingly precise observations, checking each finding against Newton’s laws. Then, in 1781, William Hershell, a British astronomer, discovered Uranus. In 1846, Urbain Leverrier in France and John Couch in England independently concluded that the perturbations, or disturbances of motion, in the orbit of Uranus could not be explained by the presence of other known bodies, and that an eighth planet must exist. Asked by Leverrier to watch a certain area of the sky for an uncharted, the Berlin Observatory found the predicted planet, which was named Neptune.
Below is a list of the most important discoveries in space exploration history:
The Movement of Stars and Planets:
While Copernicus rightly observed that the planets revolve around the Sun, it was Kepler who correctly defined their orbits. At the age of 27, Kepler became the assistant of a wealthy astronomer, Tycho Brahe, who asked him to define the orbit of Mars. Brahe had collected a lifetime of astronomical observations, which, on his death, passed into Kepler’s hands. (Brahe, who had his own Earth-centered model of the Universe, withheld the bulk of his observations from Kepler at least in part because he did not want Kepler to use them to prove Copernican theory correct.) Using these observations, Kepler found that the orbits of the planets followed three laws.
Like many philosophers of his era, Kepler had a mystical belief that the circle was the Universe’s perfect shape, and that as a manifestation of Divine order, the planets’ orbits must be circular. For many years, he struggled to make Brahe’s observations of the motions of Mars match up with a circular orbit.
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.
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.
The Theory of Relativity:
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.
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.
The Expanding Universe:
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.
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.
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.
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.
Cosmic Microwave Background Radiation:
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.
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.
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.
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!
- We have eight planets in our Solar System. However, outside of our Solar System there are thousands of other planets. The extra-solar planets or exo-planets are in orbit around another star. So far we have almost 1800 confirmed new worlds, with another 3000 awaiting confirmation. Astronomers are looking to a star’s goldilocks zone for planets that may be habitable, just like the Earth. The majority of planets discovered so far are hot gas giant planets.
- This is tricky one to get your head around but a year on Venus (that is the length of time it takes to complete one whole orbit around the Sun) is 224.7 Earth days. However it takes 243 Earth days to rotate on its axis just once.
- Ancient astronomers once believed the Earth was at the centre of the Universe but now we know that the Sun is at the centre of our Solar System and our planets orbit the Sun. The Sun makes up 99.8% of the entire mass of the whole Solar System. One million Earths would be needed to be the same size as the Sun.
- Space officially begins at the universal marker of the Karman Line. This invisible boundary is 100km above the Earth. In theory if you could drive your car upwards, you could be in space in less than hour.
- This is a pretty gross fact but in the micro-gravity environment, astronauts are not using their feet to walk. Therefore the skin on their feet starts to soften and flakes off. As laundry facilities do not exist in space, astronauts will wear the same underwear and socks for a few days. Those socks then need to be taken off very gently. If not those dead skin cells will float around in the weightless environment.
- There is a famous image of President Nixon talking to the Apollo 11 crew consisting of Michael Collins, Neil Armstrong and Buzz Aldrin. This continued until after the Apollo 14 crew returned safely. After this it was decided that the Moon did not contain any deadly diseases. The Apollo 13 crew, who had a malfunction and had to return to Earth, did not have to be quarantined after their re-entry as they didn’t actually walk on the moon.
- Another change to the human body in micro-gravity is that spine straightens out, as gravity is not pushing you down. In fact you can be up to as much as 5cm taller in the Space Station.
- Even though Mercury is the closest planet to the Sun, it is not actually the hottest. Mercury does not have any atmosphere meaning that this planet is only hot in the daytime when it is directly facing the Sun. At this stage temperatures can rise to 425°C but at night the planet’s temperature can drop down to a freezing -180°C. Venus is the hottest planet. Its thick clouds trap the Sun’s heat causing Venus to be a sizzling 500°C all of the time!