Astronomy Test Unit 2

Optical telescopes

lenses and mirrors

they have two major types refracting and reflecting/newtonian( invented by Issac Newton)

optical

relating to sight

refract

refers to bending of light through lenses

reflect

refers to bouncing of light from mirrors

main objective of a telescope

to gather more light than can be seen with the naked eye

this can be achieved by larger openings and longer exposure

often referred to as “light buckets”

Parts of a refractor telescope

objective lens and eyepiece(another lens)

Problems with refractors

chromatic abberation and large lenses which make it heavy

Parts of reflector telescopes

primary mirror, secondary mirror, and eyepiece(lens)

Reflectors (aka Newtonian)

Most modern telescopes( ex. Hubble and James Webb)

In all telescopes the image is…

upside down

from this you get the best image

correction lenses/mirrors reduce the amount of light

Location for telescopes

optical telescopes have trouble with atmosphere and water vapor so the solution is to go higher and drier and also to have darker skies

Connection between astronomers and light

this is the only way an astronomer can observe anything beyond earth

Visible light

a type of electromagnetic radiation (ex. infrared, radio, x ray, and ultraviolet)

atmospheric window

not all light can pass through Earths atmosphere only radio waves and visible light can pass through

What does infrared travel better through

dust clouds

limitations

visible light does not come from very distant objects

cannot see through dust of the Milky way galaxy

only visible light and radio waves visible from ground

Speed of light

travels about 186,000 miles per second

Tycho Brahe

Made the most detailed astronomical measurements to date

Johannes Kepler

Used Tycho Brahe’s dat to finally understand the motion of planets

period

time it takes to orbit

semi major axis

kinda sorta the distance to the star

Keplers laws

the motion of the planets is elliptical not circular

Orbits sweep out equal areas during equal times

The square of a planets orbital period is proportional to the length of the semi major axis

Keplers second law (equal areas, equal times)

Planets do not move in circles they move in ellipses and they move faster when close and slower when further away aka slingshot effect

Galileo Galilei

An objects natural motion is to move in a straight line and at a constant speed

Isaac Newton

Three laws of motion first one was galileos

Newtons Laws of motion

Constant motion(natural motion, constant speed, same direction, no force needed)

Acceleration( F=MA, force is related to acceleration, force is related to mass)

Action and reaction( Reaction force is opposite direction equal amount)

Aristotle

ancient greek philospher

said motion is either natural or violent

Newtons first law of motion

An object at rest stays at rest and an object in motion remains in motion at a constant speed and direction unless acted upon by an unbalanced force

Inertia

tendency of an object to resist changes in motion

Newtons second law of motion

Force is directly related to acceleration

F=MA

any acceleration must be the result of a force

Newtons third law of motion

Forces come in pairs you cant touch without being touched and for every action there is an opposite and equal reaction