Asked by: Zahi Assir

We know the Earth goes round the Sun, all the way around is 2 radians (360 degrees). We also know that it takes a year (approx 365 days) which is therefore about 3.2x10

Therefore = 2 / 3.2x10

However, if we can measure the distance to the Sun we can also calculate the velocity of the Earth relative to the Sun. Although unless we define a direction this is more technically known as the speed. This can be done by looking at the definition of the radian. The radian is a unit which conects the radius of an arc, the length of the arc and the angle subtended by the arc. The formula for this is s = r x (where s is the length of the arc, r is the radius and the angle). So if we know the radius of the Earth's orbit (1.5x10

So, the Earth travels through space (relative to the Sun) at: v = 2.0x10

Answered by: Edward Rayne, Physics Undergraduate Student, Cambridge UK

'The atomic bomb ... made the prospect of future war unendurable. It has led us up those last few steps to the mountain pass; and beyond there is different country.'**J. Robert Oppenheimer**

(*1904-1966*)

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