While humans may have stopped travelling beyond near-earth orbit since the end of the moon missions in the 1970s, we have learned more about the universe beyond our orbit in the past 40 years than ever before. Here are just some of the most interesting facts about our solar system and the universe beyond.
1. Pluto Isn’t The Only Dwarf Planet
When the International Astronomical Union amended the definition of a planet in 2006, relegating Pluto to the status of a dwarf planet, many were surprised to learn of the existence of other dwarf planets which would keep Pluto company in this category of smaller celestial objects. Eris, Haumea, Makemake and Ceres, which is located within the asteroid belt between Mars and Jupiter, are all dwarf planets alongside Pluto by the 2006 IAU definition.
2. Saturn Has Huge Hurricanes
While hurricanes and typhoons on Earth can be incredibly destructive forces, those that have been observed on Saturn are even larger and faster. In 2013, the Cassini spacecraft, which has been observing the planet since 2004, took pictures of a hurricane roughly 20x larger than the average ones you might find on Earth, with an eye 1,250 miles across. Even this mega-storm isn’t a record-holder however, with Cassini snapping a storm at the planet’s south pole with an eye 6,000 miles across, a full five times larger than the one observed in 2013.
3. Almost All Of The Solar System’s Mass Is The Sun
While most people are aware of just how much bigger than Earth planets like Jupiter (22 times wider) and Saturn are (18 times wider), these huge planets are made up of less dense material than asteroids, some moons and smaller planets like Earth and Mars. Because of this, 99% of the mass in the entire solar system is held within our parent star, the Sun.
4. There Are A LOT Of Stars In The Universe
We are located within a galaxy known as the Milky Way, within which are somewhere between 200 and 400 billion stars, each of which could potentially have one or more planets orbiting it. Conservative estimates state that there are anywhere from 100 billion up to 1 trillion galaxies in the observable universe, giving a potential total of stars in the universe of 1022 to 1024 (10 sextillion-1septillion). It’s enough to make your brain ache.
5. A Supernova Can Be Seen From Earth
When a very large and massive star dies and goes supernova, it causes a huge explosion which throws out enormous amounts of light and radiation in a shock wave which travels at up to 30,000 kilometres per second. On average, it is believed that three supernovas occur in our galaxy every century, and at least one has been observed on Earth with the naked eye. In 1604, Johannes Kepler noted that a ‘new star’ had appeared in the sky, which was visible even during daytime for as long as three weeks.
6. What’s Left Behind Can Be The Densest Thing We Know Of
As a star goes supernova, most of its mass is ejected in the explosion and flies off into space, however the central region of the star collapses due to gravity. As it does so, protons and electrons combine together to form a relatively small but highly dense mass of particles, known as a neutron star. Neutron stars are generally only around 12 miles across, yet have anywhere between 1.5x and 3.2x the mass of our Sun, which itself is 218 times wider than Earth. To put this into perspective, this would be equivalent to a sphere as wide as Brooklyn in New York weighing 500,000 times as much as the entirety of Earth.
7. Even The Closest Stars Are Moving Away From Us
The universe is constantly expanding, with the very fabric of space being stretched out as it does so. It is for this reason that, even though the universe is reckoned to be approximately 13.79 billion years old, the edge of the observable universe is likely to be as much as 47 billion light years away. If humans could one day somehow travel to other solar systems, the journey back to Earth would be further than the initial, outgoing journey was.
8. If The Sun Exploded, You Wouldn’t Even Know It
It seems incredible to think that this huge ball of burning gas that is responsible for us even being able to survive on this floating rock is so far away, it could disappear without us realising. The key here is physics’ old friend the speed of light, the fastest that anything is believed to be able to travel. The energy released by the sun collapsing in upon itself would speed towards the earth at near to or the same speed as the sun’s life itself, meaning that for the 8.5 minutes it takes for light to travel from the sun to Earth the Sun would not even exist and we would be absolutely clueless. But…
9. Life On Earth As We Know It Will Be Dead By Then
In the grand lifetime of a star, our sun is in its prime at the age of around 4.57 billion years old. However, it is halfway through its ‘main sequence’, during which it converts around 600 million tons of hydrogen to helium in its core every second. As time goes on and helium builds up, the sun burns more and more hydrogen, gradually increasing the amount of energy it emits – in 1.1 billion years’ time, the sun will be 10% brighter than today. This will cause an unstoppable greenhouse effect, similar to that observable on Venus, and all water in the atmosphere will evaporate off into space. After 3.5 billion years, all the oceans will boil and Earth’s transformation into a hot, desert planet will be complete.
10. The Sun Will Never Explode Naturally
While it is fun to speculate about what might happen if the Sun exploded, it simply doesn’t have the mass necessary to cause a supernova as it dies. Instead, when the sun’s core runs out of hydrogen in about 6 billion years’ time, all the helium ash will collapse upon itself, heating the sun’s inert core and causing it to expand. The new ‘red giant’ sun will grow so large that it will engulf Mercury, Venus and eventually the Earth, potentially growing so large that its radius alone would be the current distance between Earth and the Sun, 92.96 million miles.
