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.
Does it rain diamonds on Neptune?
Very probably, and in 2017 scientists made it happen on Earth. Deep inside Neptune and Uranus, pressure and heat are thought to squeeze carbon out of methane and crush it into diamonds that sink toward the core. A team at the SLAC National Accelerator Laboratory recreated those conditions with a laser and watched diamonds form.
How much would a sugar cube of neutron star weigh?
About a trillion kilograms, according to NASA. A neutron star packs more mass than the Sun into a ball roughly 20 kilometres across, the size of a city. That makes its material so dense that a piece the size of a sugar cube would outweigh every car, truck and bus on Earth put together.
Is there a planet where it rains glass sideways?
Yes. HD 189733b, a gas giant 63 light-years away, is a deep cobalt blue because its clouds are laced with tiny particles of silicate, which is to say glass. The side facing its star is around 1,000 degrees Celsius, and winds of roughly 7,000 kilometres an hour would blow the glass rain sideways.
Are the Apollo astronauts' footprints still on the Moon?
Yes. The Moon has no wind, rain or weather to wear them away, so the bootprints and rover tracks left between 1969 and 1972 are still in the dust. NASA's Lunar Reconnaissance Orbiter photographed the landing sites from orbit, and the astronauts' paths show up as dark trails.
Is the Sun losing weight?
Yes, about four million tons a second. Deep in its core the Sun fuses roughly 600 million tons of hydrogen into helium every second, and about four million tons of that mass does not come out the other side as matter. It leaves as pure energy, which is the sunlight.