## Saturday, June 9, 2012

After the Venus transit let me present you a challenge.
Transit of the planets is a way to discover another planets (exoplanets) in distant stars.
 Credit: Astromic Backyard
Venus is almost the same size of our planet. So, how many Earths could be inside our Sun, if could be that possible?
Let's assume that Earth, by approximation, is a little sphere that we going to put inside a giant sphere, our Sun.
To calculate how many our Sun is large in volume than our Earth, we find the relation between both astronomical objects. So, we can establish the volume ratio between Sun and Earth:
VSun = X x VEarth ↔ X = VSun / VEarth    [1]
The sphere's volume can be calculated using the mathematical expression
4/3 π R3
Thus, applied in the equation [1] brings:
X = (4/3 π R3Sun) / (4/3 π R3Earth) ↔  X = (R3Sun) / (R3Earth)     [2]
We can find the Sun and Earth radius values in Wikipedia:
R(Sun) = 6,955×105 km       e        R(Earth) = 6 378,1 km
 Credit: NASA
Replacing in equation [2] and solving, we obtain:
X = (R3Sun) / (R3Earth)   ↔   X = (6,955×105)3 / (6 378,1)3   ↔  X = 1 296 634,0
That result means that our Sun is more than one million times largest than Earth. Thus, we can put about 1,3 x 106 Earths inside our Sun!

Here is a playlist with videos about stars, Solar System and more.