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Cool Facts about Space

This is a collection of what many people find fascinating about the universe beyond Earth — drawn mostly from the fields of cosmology, astronomy, and astrophysics. Each of these should facts should be mysterious, impressive, surprising, or non-intuitive. The point is to be intellectually stimulating.

Our Solar System

1.
Our Solar System is flying through space at ~514,000 mph around our galactic center.
2.
One galactic year is 225-250 million terrestrial years.
3.
Every planet in our solar system rotates in the same direction around our sun, which is counter-clockwise from the point of view above our north pole.
4.
Every planet in our solar system — except Venus — rotates around its own axis in a clounter-clockwise direction from the point of view above our north pole.

Our Sun

1.
The sunlight we experience on the Earth took about 30,000 years to get here from the centre of the sun. The photons bounce around inside the sun and eventually exit then travel about 8 minutes to the Earth.
2.
Our sun is gradually brightening.
3.
It will grow into a red giant and engulf the earth in about __ billion years.
4.
Produces most of the nutrinos that hit each. Each second, about __ billion neutrinos flow through each square inch of your body. Neutrinos don't affect most matter.

Mercury

1.
Mercury has a surface that's more cratered that most planets because it has no atmosphere to slow down meteors.

Venus

1.
Spins in the opposite direction to all the other planets in our solar system. It's believed this is the case because something collided with it.
2.
It's atmosphere is 92x denser than Earth's
3.
It's days are longer than its years.
4.
It's the only known planet inhabited entirely by *dead* robots
5.
It's speed of rotation about its axis varies much more than other planets in the solar system. This is believed to be because it's atmosphere moves quickly across its surface, rotating around the planet about once every 4 Earth days. This pushes on its mountains in complex ways, changing the speed of rotation.

Earth

1.
Flies through space at 1000 miles/s
2.
It's rotation is slowing gradually as the moon spirals away from us.
3.
Long ago, we used to have 400 day years and 22 hour days.
4.
It rotates around itself counter-clockwise from a point of view above the north pole.
5.
It rotates around sun clounter-clockwise from a point of view above the north pole.

Our Moon

1.
Has a far side that always faces away from the Earth. It used to rotate but was slowed from 7 meter high rock tides.
2.
The far side has more craters than the near side.

Mars

1.
One of its moons, Phobos, will be torn apart in 20-40m years and form a ring around the planet
2.
Is the only known planet inhabited entirely by robots.

Jupiter

1.

Saturn

1.
It's rings are ~20m high, made partly of pure ice, 1cm-1km across
2.
Has moons embedded in its rings

Uranus

1.
Is pronounced "YOUR-a-nuss"
2.
Is thought to contai trillions of diamonds.
3.
Has the coldest surface among all our planets, at -224c, but below the surface is a boiling ocean with diamods at the bottom.

Neptune

1.
It's winds move as fast as an Earth jet.

Pluto

1.
Is a binary dwarf planet.
2.
Is part of the kuiper belt with many other similar-sized objects.

Comets

1.
Usually come from Kuiper Belt.
2.
Have 2 tails — one made of dust, the other made of ionized gas that faces away from the sun (not behind the direction of travel).

Our Galaxy, The Milky Way

1.
Is presently colliding with another galaxy called Canis Majora Dwarf.
2.
Will collide with the Andromeda Galaxy in 3-5 billion years.

Humans in Space

1.
In space, the human body doesn't die by feezing, like in movies. It boils itself because the heat it generates cannot escape quickly. Empty space is an insulator.
2.
Astronauts in any space container like a space capsule/station/shuttle require air circulation. Otherwise, invisible CO2 bubbles form. They'll suffocate if their head is inside one.

The Universe

1.
The Universe began with the "big bang" and is growing by stretching like latex fabric in three dimensions. Because the expansion is space itself, rather than things through space from a single point, there's no single "big bang location".
2.
The universe is expected to expand forever. Our best physics model, based on the matter and energy we observe, doesn't explain why the universe is expanding, or why the rate of expansion is getting faster. We've invented Dark Energy to explain this, which is thought to be a weak repulsive force that all space exerts upon itself, pushing space apart, though we've never observed Dark Energy.
3.
Turns out there's something that can travel faster than light. Space itself. The speed of light governs travel through space. Turns out that the expansion of space itself results in distance points moving away from each other faster than light.
4.
The farthest-away parts of the universe are moving away from us faster than the speed of light. Most of the light from this region can't reach us. However, as the rate of expansion increases, some of this light will be able to reach us.
5.
Distant parts of the universe are moving away from us faster than light, which is a "causal horizon" beyond which we'll never see, affect, or be affected by. Within this horizon, relative to us, is the "observable universe", and it's getting smaller. After enough time, the observable universe will include only our own galaxy (and galaxies like Andromeda that will collide with us).
6.
The lifecycle of the universe is expected to enter a phase where all matter and energy collects into black holes. Then, as the black evaporate into hawking radiation, it's believed that there will be only hawking radiation.
7.
Gravity travels at the speed of light. So if our Sun suddenly disappeared, the Earth would keep on rotating around where the Sun used to be, for about 8 minutes, while we continue to receive the gravity in transit.

Galaxies

1.
Galaxies rotate about once every 1 billion years, regardless of their size.
2.
Most galaxies have supermassive black holes at their center. They're also believed to commonly have swarms of smaller black holes that are spiraling into the supermassive black hole.
3.
Based on our best physics models and observational data, the rate that suns orbit in galaxies should go down the farther the sun is from the galactic center. However, suns actually orbit at near-constant speed, regardless of how far they are from the galactic center. This seems to be the case in every galaxy. Our best explanation for this is an unobserved Dark Matter halo around each galaxy, though we've never directly observed Dark Matter.

Planets

1.
Many planets are orbiting their suns such that the same face of the planet is always oriented towards the sun. These are called "eye-ball planets" because they are thought to resemble eyeballs. There's a light side that's very hot, a dark side that's very cold, and a ring between these sides that's a transition zone.