Suntrek homepage

Factary

Y - Factary

YOHKOH

No - not John Lennon's wife (not even the same spelling)!

The name of a Japanese satellite, launched in 1991, which gave detailed images and spectra of X-rays from the Sun. The name means 'sunbeam' in Japanese. One of Yohkoh's instruments was built in the UK.

Unfortunately, after many years of successful operation, Yohkoh stopped working in December 2001. Even so the data it produced are still being used in many solar physics research projects.

Find out more about YOHKOH

Yotta (Y)

A prefix indicating a million billion billion of something.

In numbers it can be written as 10²⁴ or 1 000 000 000 000 000 000 000 000

An example could be the distance to the Andromeda galaxy. That galaxy is the most distant object that can be seen with the naked eye. Usually it is described as being 2 million light years from us, but we could also say it is 0.02 yottametres from us. So 1 yottametre is 50 times as far as the distance to the Andromeda galaxy.

Or closer to home - the volume of the Earth is about 1.1 x 10²⁴ litres or about 1 yottalitre.

Not a yotta people know that!

Yocto (y)

A prefix indicating a billion billion billionth of something.

In numbers it can be written

10^-24 or 0.000 000 000 000 000 000 000 001

The mass of a single proton is 1.67 yoctograms!