Astronomy Flashcards
How to remember the order of the planets?
My (mercury) Very (venus) Excellent (earth) Mother (mars) Just (jupiter) Sent (saturn) Us (uranus) Nine (neptune) Pizzas (pluto)
Where is the asteroid belt in our solar system?
In between mars and saturn
Relationship between Orbital speed, time period and orbital radius
Orbital speed = (2 x pi x orbital radius)/time period V = 2(pi)r/t
How do you convert km to km/day into km/s?
Divide it by (24 x 60 x 60)
What is the gravitational field between two objects INVERSELY proportional to?
The distance between them squared
What does gravitational force do?
- Causes the planets to orbit the sun
- Causes the moon and artificial satellites to orbit the earth
- Causes comets to orbit the sun
What are comets?
Icy mud balls with elliptical orbits
When are comets travelling fastest and why?
When they are closest to the sun
Because this is when the sun’s gravitational force is the strongest
Where do the tails of comets always point and why?
Away from the sun because it is blown by solar wind
What is our solar system a part of?
The milky way galaxy
What does the size of the gravitational force between objects depend on?
- The size of the masses involved. Large masses, like stars and plantets, produce large gravitational forces. Smaller bodies lke the moon have much smaller gravitational forces.
- The distance between masses. The greater the distance between two masses the smaller the gravitational force between them.
What is the equation for weight?
weight = mass x gravitational field strength
Describe the orbit of a comet
It has a highly elliptical orbit around the sun (planet orbits are more circular). Their orbits take them from the vicinity of the sun to the outer reaches of the Solar System, crossing orbits of the planets as they do so
What is a galaxy?
A large collection of billions of stars
What is the universe?
A large collection of billions of galaxies