Archive for the ‘Did You Know’ Category

How to Find a Planet Measuring Star Coordinates

October 4, 2009

Finding planets near other stars is a cutting edge in modern astronomy. How exactly do they do it? There is no simple answer on this, because there are several ways to do it.

1. Measure precise star position. If star has a planet, then planet affects star position, because they both circle around common center of mass. If you think that stars are too big and heavy to feel any gravitational effects from their planets, look at the picture below.

This is how center of mass (every Solar system object spins around this point) moved. As you see sometimes it even goes out from the Sun. Image from: answers.com

This is how center of mass (every Solar system object spins around this point) moved. As you see sometimes it even goes out from the Sun. Image from: answers.com

As you see planets in the Solar system make the Sun spin around common center of mass. Exoplanets can do this to their stars and we can detect (sometimes :-)) those position shifts and tell that star has a planet. But in order to do this very precise instruments are required and also this method works only for stars which are close to us.

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Hydrogen Bomb Physics Explained

August 23, 2009

I noticed that many people come to my post about the Sun while looking for a hydrogen bomb. I don’t think it’s right, so for all those who seeks information about what hydrogen bomb is and how it works I wrote this post.

Hydrogen bomb, h-bomb or thermonuclear bomb is based on a process called nuclear fusion. There are two different processes in nuclear physics: fusion and fission. They sound very similar, but mean different stuff.

Nuclear fission: big atom (for example uranium) splits into parts, usually smaller atoms (for example barium and krypton) of lighter elements, and energy is emitted during this process. Nuclear bombs and nuclear power plants are based on this process.

Nuclear fusion: several light atoms (for example hydrogen) combine one bigger atom (for example helium) and energy is emitted during this process. Thermonuclear (or hydrogen) bombs are based on this process, stars get their energy from this process as well. Humanity is still working on making a first thermonuclear power plant (to build a bomb is much easier than a power plant :-)

Why do we fight for nuclear fusion and why is it better than our current nucler power plants? The answer is simple: it gives much more energy, and we have a lot of fuel here on Earth (so called heavy water, there is plenty of it in the ocean).

Here are some photos and videos related to hydrogen bomb (since that’s the reason I wrote this post in a first place):

Edward Teller -- one of the hydrogen bomb inventors. I didnt know his name before, so I found it in wikipedia for you to save some time. He worked on nuclear bomb project and later on hydrogen bomb. This image is from wikipedia.

Edward Teller -- one of the hydrogen bomb inventors. I didn't know his name before, so I found it in wikipedia for you to save some time. He worked on nuclear bomb project and later on hydrogen bomb. This image is from wikipedia.

This is the first full scale test of hydrogen bomb called Ivy Mike performed in November 1952 by Americans:

This is the biggest hydrogen bomb ever exploded, the Tsar Bomb, October 1961 by Russians:

What is a Temperature in Space

August 19, 2009

You probably often read about gas or dust in space being that much hot or cold. But what does is actually mean? Does one atom or molecule have a temperature already? Thanks to physics we can answer these questions already. We were able to link temperature (the thing we actually feel as warm or cold) with the speed of molecules. The faster molecules move — the higher temperature is and vise versa. This simple law allows us to talk about temperatures in space without using thermometers we all got used to here on Earth. Video below explains how come velocity and temperature is actually the same thing: