Farts Aren't Invisible (eBook)

CHAPTER 2

THE SOLAR SYSTEM AND THE UNIVERSE

You can still hear the remnants of the Big Bang.

All you need is a radio receiver. When our universe was formed from a single point in what is known as the Big Bang 13.8 billion years ago, it was super-hot. It has been expanding outwards and cooling ever since and, although space is now very cold, there is still leftover heat – known as the cosmic microwave background (CMB) – which can be detected by microwave telescopes as a glow pervading the whole sky. Unfortunately, it can’t be seen by the naked eye because it is so cold, a mere 2.725 degrees above absolute zero (–273.15° Centigrade), but you can hear it, a genuine echo of the Big Bang. In 1964 astronomers Arno Penzias and Robert Wilson were using a radio antenna to measure signals from space and were puzzled by a sound they thought at first was just interference. But it was coming uniformly from all over the sky. They had detected the CMB and it won them the Nobel Prize for physics.

*  *  *

There’s something missing from our universe. Well, it’s not missing but we can’t find it. Yet. Cosmologists have realised that all the stuff we can see in space, such as galaxies, is only a fraction of the mass of the universe. Something else is filling the gaps. We can’t see it but we call it dark matter because it doesn’t emit or absorb light. Its close cousin is called dark energy, which is causing the universe to expand faster, almost like the opposite of gravity. Dark matter matters because without it the universe doesn’t work. It holds everything together like dough filling the gaps between currants in a bun. We know it’s there because we can see it bending light from distant stars and it stops galaxies tearing themselves apart as they spin. One day we’ll figure out what it is.

Black holes are so dense and therefore their gravity so strong that not even a ray of light can escape their clutches. Hence their name.

Neutron stars are very dense too. They are the remnants of giant stars that died in a fiery explosion known as a supernova. They have a mass of about twice that of our Sun and are the smallest and most dense stars known to exist. One teaspoon of material from a neutron star would have a mass of about 4 billion tonnes.

Our solar system is approximately 4.6 billion years old. The oldest planet is the giant blob of gas that constitutes Jupiter – twice as massive as all the other planets combined – which formed about 3 million years after the birth of the solar system.

Earth formed about 60 million years after the solar system began to coalesce (although some creationists wrongly believe that it’s only around 6000 years old).

Earth is slowing down by about 1.7 milliseconds a century. Originally a day on Earth lasted only about six hours. Now, of course, it’s 24. And the Moon is to blame. It creates the tides in our oceans, which bulge and create a twisting force that slows down the Earth’s rotation.

Asteroids up to 50 metres in diameter, with some as big as 400 metres, pass between Earth and the Moon on average about once every two years. Small ones, a few metres in diameter, pass through several times a month.

The largest asteroid yet discovered is Ceres, 965 kilometres across. It was spotted in 1801, long before many of the solar system’s planets. It accounts for more than a third of the mass of the asteroid belt that is located between Mars and Jupiter.

NASA’s DART mission to adjust the orbit of an asteroid by crashing into it (useful if it is on a collision course with Earth) worked. In 2022 the spacecraft struck its target Dimorphos and reduced the time it took to orbit its parent asteroid Didymos, by 32 minutes.

One day on Venus lasts a whopping 5832 hours, or about 243 Earth days (which is longer than a year on Venus lasts – 225 days). Just because the planet rotates slowly on its axis doesn’t mean it can’t travel quickly around the Sun.

One day on Jupiter lasts only 9 hours 56 minutes, the shortest in our solar system.

Pluto’s year is 90,520 Earth days (or 248 years), the longest in our solar system.

Venus is so inhospitable, with high temperatures of up to 475°C and an atmospheric pressure 90 times that of Earth, that when the Soviet Union’s Venera spacecraft landed there between 1966 and 1983 their systems lasted mere minutes before the probes were melted or crushed.

All planets orbit the Sun in the same direction, but Venus is the only planet that, as it does so, rotates east to west, meaning that the Sun on Venus rises in the west.

Uranus rotates on its side, appearing to roll around the Sun like a ball.

The planet with the most moons is Saturn, with 145. It recently took the record from Jupiter (which has 92) in May 2023, when 62 new moons were discovered. But new moons are being discovered all the time. Jupiter may one day top the list again.

Mercury and Venus are the only two planets in our solar system with no moons.

The Sun takes up 99.86% of the mass of our solar system. However, it is very slowly losing mass as it produces energy.

1.3 million Earths, by volume, could fit inside the Sun. That’s if you squished them up.

We know the universe is expanding because we can observe other galaxies speeding away from ours. In the same way an ambulance siren changes pitch after it passes us and its sound waves are stretched out, the same happens to light waves coming from galaxies. The waves are stretched and appear redder. The faster the galaxy is moving, the redder its light. This is known as “red shift”.

If two pieces of metal touch in space they will permanently bond in a process known as cold welding. Merely the pressure of the metals touching in a vacuum is enough. On Earth, the atmosphere will always leave some molecules of air or water between the metal pieces, but in space these aren’t present.

Sunlight takes 8 minutes 20 seconds to reach Earth.

In our solar system active volcanoes are only found on Earth and on Jupiter’s moon Io. We know there are inactive volcanoes on Venus, Mars, Mercury, and our Moon. There may be active volcanoes on Venus and Jupiter’s moon Europa, but we can’t tell because Venus has dense cloud cover and Europa is covered in thick ice sheets.

Venus is the brightest planet in the solar system with an albedo of 0.75. Albedo is a measure of an object’s reflectivity. By comparison the Earth’s albedo is 0.305. Venus is so bright because its thick, sulphuric acid clouds reflect most of the sunlight it receives.

The biggest storm in the solar system is Jupiter’s Great Red Spot, an elliptical-shaped anticyclone clearly visible on the surface of the planet, south of its equator. It has been raging for at least four centuries, has winds of up to 430 kilometres per hour and could fit about three Earth-size planets inside it. Saturn occasionally has more powerful storms but none are as enduring as the Great Red Spot. The spot does, however, appear to be shrinking.

The highest temperature on the Moon in direct sunlight can reach 120°C, the lowest at the poles and in shadow is –250°C. The lack of atmosphere means the warming effect from the Sun’s rays is intense, but this same lack of atmosphere on the Moon and in space means there is no other warming effect. Once you are in shade, the temperature plummets. Similarly, when the Sun strikes the surface of a spacecraft, its surfaces expand rapidly while the shaded sides cool and contract. This can obviously lead to potential catastrophic structural defects, and it is why spacecraft always rotate during flight.

Are we all – animals and plants alike – descended from aliens? It’s a theory, known as panspermia, that has waxed and waned over the centuries, but the suggestion is that bacteria or other microscopic life forms that evolved elsewhere in the universe could have been carried to Earth on meteorites, space dust, asteroids, and comets before evolving into higher forms of life. It’s now a subject of serious scientific research. It seems microscopic organisms can survive the collisions necessary to be ejected from their host planet, travelling through the vacuum of space, and the impact of striking another planet. Which means your great-great-great-ancestor might have been a cold virus from the Andromeda galaxy. That’s nothing to be sneezed at …

The first person to suggest the theory of panspermia was the 5th-century Greek philosopher, Anaxagoras. In the 20th century, to much scepticism, British astronomer Fred Hoyle and his protégé Chandra Wickramasinghe were modern-day proponents of the theory. Wickramasinghe would later prove that some interstellar dust was organic. Both believed that life forms continue to enter our atmosphere, giving rise to new diseases. Cue more sneezing …

Around two-thirds of the atoms in human bodies are hydrogen atoms that are almost as old as our universe (13.8 billion years old). However, hydrogen is very light, so this only accounts for about 10% of our mass. Most of the rest of the atoms in our bodies – mainly oxygen and carbon, but also including elements such as magnesium, nitrogen, calcium, and sulphur – were created inside stars by nuclear fusion reactions.

MYTH BUSTING

Myth: Space is a vacuum.

It isn’t, at least not completely. It...