Odd truths about space
Planets behaving badly, and numbers that stop making sense.
Is a day on Venus longer than a year on Venus?
Yes. Venus takes about 243 Earth days to spin once on its axis, but only about 225 Earth days to travel all the way around the Sun. A Venusian day is longer than a Venusian year.
Would Saturn float in water?
On average, yes. Saturn's mean density is about 0.69 grams per cubic centimetre, lower than water's 1.0, making it the only planet in the solar system less dense than water. Given a big enough bathtub, it would float.
Is the Moon moving away from Earth?
Yes. The Moon drifts about 3.8 centimetres further from Earth every year — roughly the rate your fingernails grow. It is a direct measurement, not a model, taken by bouncing lasers off reflectors the Apollo astronauts left behind.
Are there more trees on Earth than stars in the Milky Way?
Yes, by a wide margin. A 2015 study in Nature put the global tree count at roughly 3.04 trillion. The Milky Way is generally estimated to hold somewhere between 100 and 400 billion stars — around ten times fewer.
Are there more possible chess games than atoms in the universe?
Yes. The number of possible chess games is estimated at around 10^120, known as the Shannon number. The observable universe contains roughly 10^80 atoms. Chess outruns it by about forty orders of magnitude.