Download Explanation of Newton's and Kepler's Laws: Inertia, Gravity, and Planetary Orbits - Prof. and more Study notes Astronomy in PDF only on Docsity!
Math Lab (can be of help with your math) Warf 12?
MTh 9 6 F 94
Isaac Newton (English)
Inertia is an object's tendency to
resist changes in its motion. Mass
the measurement of an object's
inertia.
1st Law of Motion:
A body remains at rest or moves in a
straight line at a constant speed
unless it's acted upon by a net,
outside force.
2n Law of Motion:
The rate at which an object's motion changesits
acceleration is directly proportional to the force applied to
it, and inversely proportional to its mass.
Force = mass X acceleration
F = ma
Note: acceleration can be speeding up, slowing down, or
turning.
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3rd Law of Motion:
For every applied force, there is an equal but opposite
"reaction" force.
The motion of a rocket is a good example of the 3rd law:
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Kepler's 3 laws of planetary motion can be derived from
Newton's law of gravitation and (Newton's) 3 laws of motion.
To make it work out just like Kepler's laws, you have to
assume that a) the Sun is much heavier than any of the
planets and b) the planets don't pull on each other.
Where we have
pairs of stars
orbiting each other,
we can use this to
find the stars'
masses
We've also used this to discover massive planets orbiting
other stars. (A star will "wobble" around a bit as a planet
orbits it.)
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Light & Telescopes
Light is form of electromagnetic (EM) radiation, energy that travels as EM waves.
Light (& all EM waves) travel at a speed denoted by "c": c = 300,000 km/s = 3.00 x 10 186,000 miles/s
Wavelength ( "lambda") is the distance between successive waves.
Different colors of ligthits spectrumare just waves of different wavelength.
There are other EM waves with wavelengths less than 400 nm and longer than 700 nm. These collectively make up the EM spectrum. From long wavelength to short wavelength, these waves are:
radio, infrared (IR), visible, ultraviolet (UV), xray, gammaray
Our atmosphere blocks a lot of the EM waves that come to us from space. The extent to which it blocks a particular wavelength is called theopacity. It has a low opacity to visible light, but a high opacity to gammarays.
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Telescopes: Two main types of telescopes:
reflecting telescopes (reflectors) use a curved mirror to collect & focus light.
refracting telescopes (refractors) use lens to collect & focus light.
Larger telescopes are better. Why? Increased lightcollecting ability. Most of the objects in the sky are dim. We need collect a lot of light to see them well.
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Increased angular resolutiona larger telescope lets you
see more detail in an object
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