Kepler’s Laws of planetary orbits explain why the planets move at the speeds they do. You’ll be making a scale model of the solar system and tracking orbital speeds.
Kepler’s 1st Law states that planetary orbits about the Sun are not circles, but rather ellipses. The Sun lies at one of the foci of the ellipse. Kepler’s 2nd Law states that a line connecting the Sun and an orbiting planet will sweep out equal areas in for a given amount of time. Translation: the further away a planet is from the Sun, the slower it goes.
Please login or register to read the rest of this content.
If Pluto is 39.53 AU from the sun (you can look this value up and use it), and the Earth is 1 AU from the sun, then if Pluto is now scaled to be 50 miles from the sun, you’d do this:
where x = the scaled distance from the earth to the sun in miles. Do the math to get: (50 miles x 1 AU) / 39.53 AU = 1.26 AU
1.26 miles from the sun.
I think I understand where you got stuck. Have you watched this video yet?
https://www.sciencelearningspace2.com/2014/09/converting-units-of-measurement/
Most of the problems include converting the scales to bigger ones, including speed factors and different units, and I don’t really know how to do that. If you could explain it, I’d be so grateful!
Thanks,
Olivia
Which part did you get stuck on? Can you tell me more specifically how you arrived at your answer (and what you got)?
In the student worksheet packet, how do you get the answer to the first problem?
No, the further in they are to the sun, the faster they travel along their orbital path. Click here for more info:
http://www.sjsu.edu/faculty/watkins/orbital.htm
Do all the planets travel at the same speed? Ie do they all travel at 5000 mph or however fast they travel?
Wonderful! So glad you are enjoying the content! Here’s a chart for the southern sky (look near the bottom of the page). And here’s more detail about ellipses here in the upper level part of the program.
Hi Aurora,
we are really enjoying your Astronomy series. Can you point us firstly to an Australian star chart? Secondly, we are trying to understand ellipses. Can you explain why an ellipse happens rather than a circle in more detail? We are having a bit of trouble understanding this from your notes. Alternatively, can you point us in the direction of perhaps a video explaining this on the internet?
Thanks!
Josh, Caleb & Daniel (and mum Karen)
Hi Kyle! Sorry I missed answering this one right when you asked it.
I think the trouble is that Mercury and Neptune don’t have the same speeds that they travel on their path around the sun.
Neptune travels around the sun once every 60,190 Earth days. Neptune travels at an average speed of 12,253 miles per hour in its orbit around the sun. Mercury circles the Sun in only 88 days at at an average speed of 105,947 miles per hour. This is faster than any other planet in the Solar System. If both planets traveled at the same rate, you could use the proportion equation to figure out the missing quantity.
We can not figure out how to get the answer you got to question #3. We set up the problem as a proportion using distances in AU for Mercury and Neptune and then making an equation with days for Mercury to orbit versus the unknown (days for Neptune to orbit). But this does not get us close to the answer provided. Please help.
Kyle