Planet Earth is not exactly a sphere. It is rounded but it has a bulge around the equator and is flattened in the poles. Pole to pole diameter is about 27 miles (43 km) shorter than equatorial diameter. The rotation of the Earth is what causes the equatorial bulge.
Pythagoras, an early Greek philosopher (c. 570-500 b.C.), was one of the first to think that Earth shape could be spherical. This idea was suggested when he saw ships approaching from the horizon: at first he could see the masts, only when they approached he could start to see the rest of the ships.
Interested? Want to read more? You can find more about this subject here:
http://en.wikipedia.org/wiki/Earth
http://en.wikipedia.org/wiki/Figure_of_the_Earth
Friday, October 05, 2007
Thursday, October 04, 2007
What is a satellite in geostationary orbit?
A satellite is in geostationary orbit when it is positioned about 35,786km from the earth and directly above the equator. In other words, get the plane of the equator (0ยบ latitude), extend it to 35,786 km from main sea level and you find the geostationary orbit.
Satellites in geostationary orbit appear to be fixed from a given point on Earth. That's why they are so useful. You can point an antenna in a fixed direction to the satellite and it will keep the link over time. The satellite moves in the same direction planet Earth moves, and because it is in this special orbit, they both move as if they were synchronized.
You may read more about this subject here http://en.wikipedia.org/wiki/Geostationary .
Satellites in geostationary orbit appear to be fixed from a given point on Earth. That's why they are so useful. You can point an antenna in a fixed direction to the satellite and it will keep the link over time. The satellite moves in the same direction planet Earth moves, and because it is in this special orbit, they both move as if they were synchronized.
You may read more about this subject here http://en.wikipedia.org/wiki/Geostationary .
Wednesday, October 03, 2007
Welcome
Welcome to "I knew this!" !
Several times I discover that I have forgotten tiny (or not so tiny ;) ) bits of information that I learnt while I was at school. I often find out that there are many missing pieces in my general knowledge puzzle. This is what inspired me to start this blog. I want to share with you an interesting piece of information in each post. Posts will be short and right to the point. If you are like me, real busy all day, but still want to spend five minutes refreshing your memory, this blog is for you.
Several times I discover that I have forgotten tiny (or not so tiny ;) ) bits of information that I learnt while I was at school. I often find out that there are many missing pieces in my general knowledge puzzle. This is what inspired me to start this blog. I want to share with you an interesting piece of information in each post. Posts will be short and right to the point. If you are like me, real busy all day, but still want to spend five minutes refreshing your memory, this blog is for you.
