[s]Goal: 100,000 New Goal: 200,000[/s] New Goal: 250.000

[MattheHat]

right, we have 2 threads discussing planets now...

[Aiel Heart]

sun appears to move backwards in the sky from night to night--changing which background constellation it is near from month to month--the zodiac

[Aiel Heart]

Brahe had very precise measuring instruments and discovered commits and witnessed a supernova. He detected no parallax motion and so concluded that the sun goes around the earth because if the earth were moving he'd've seen parallax motion

[Aiel Heart]

*parallax motion is closer stars seeming to move in relation to background/more distant stars as earth moves and changes view of them

[Aiel Heart]

I wonder how much of this history stuff is actually going to be on the exam...

[Aiel Heart]

Brahe's assistant Kepler used the data he helped Brahe get and discovered that planets moved in a elliptical motion rather than a spherical one and that the sun is at one of the ellipses

[Aiel Heart]

the orbital speed of a planet depends on how close or far away from the sun the planet is (like a ball being swung on an ellipse at the end of a rubber band--will slow down as gravity pulls it back, spring back and around, repeat)

[Aiel Heart]

therefore Kepler didn't agree with Brahe or most others but rather thought that the sun was what was at the center of the universe not earth

[Aiel Heart]

he had data instead of logic on his side--more scientific now

[Nyanna al'Meara]

Learning more here, in the holidays, than at school XD

[Aiel Heart]

P³=a²

 

P = the amount of time it takes for the planet to make one orbit

 

a: the length of the orbit's semi major axis

Edited December 15, 2011 by Aiel Heart

[Nyanna al'Meara]

Cool!

[Smiley73]

mornings!

[Smiley73]

is this astrophysics?

[Smiley73]

if so then it is awesome

[Aiel Heart]

Galileo made many discoveries:

 

the sun has sunspots and thus isn't perfect

 

there are mountains on the moon

 

he discovered that there were 4 objects (that he could see) that orbited Jupiter--there were things that didn't orbit the earth OR the sun!!!

 

and he also discovered that Venus has phases just like the moon does--which means that both venus and earth must be orbiting the sun!!!!

Edited December 15, 2011 by Aiel Heart

[Aiel Heart]

hello :D

[Aiel Heart]

we're learning about Astronomy today

[Aiel Heart]

he was able to discover all of this with a very good telescope he made--he is called the father of modern astronomy

[Aiel Heart]

we now know what happens.... but we still don't know why

 

there is also the lack of parallax motion that must be explained

[Aiel Heart]

this guy named Newton did a lot of studying and came up with three laws of motion

[Aiel Heart]

1) A body at rest will remain at rest or a body in motion will remain in motion unless acted on by a force

A body resists change of motion

Important note: the first law ‘cares’ whether the change is in AMOUNT or in DIRECTION or both!

[Aiel Heart]

2) For a given force applied, we get a given acceleration

BUT, the AMOUNT of acceleration depends on the AMOUNT of matter present

 

F = m x a OR a = F / m

 

F= force

a=acceleration

m=mass

 

Example: The same force is applied to two objects, the more massive object is accelerated less than the less massive object

 

Force is measured in Newtons

[Aiel Heart]

3) Any two bodies with mass attract each other with the same force

 

but wait.... that means that the earth and the sun are pulling on each other the same... right?

[Aiel Heart]

WRONG