Astro final

Main Features of the celestial sphere

North celestial pole, Celestial equator(90 deg from NCP), Elliptic, Zenith(point of observer)

Right acension

Measured E/W like long with the 0 point where the elliptic meets the celestial equator

Declination

Measures N/S, 0 point is at the celestial equator

Describe altitude and Azimuth

relative to observer, altitude is height and Azimuth is angle direction

The Analemma

Tracking the position of the sun in the sky throughout the year

Constellation? Stars? Asterisms?

Cygnus the swan, Star Deneb at the back, Includes north cross

Asterism

Popular pattern that is inside of a Constellation

Cygnus the Swan, Northern cross, Deneb

Aquilla the Eagle, Altair

Aquilla the Eagle, Altair

Lyra The harp, Summer Constellation, Vega

Lyra the harp, Summer constellation, Vega

What is the summer triangle?

3 brightest stars in Lyra, Aquilla, and Cygnus, or Vega, Altair, and Deneb respectively

Bootes the herdesman, Kite asterism, Arcturus near legs

Bootes the herdesman, Kite asterism, Arcturus near legs

Ursa Minor, Polaris at handle base, Circumpolar

Ursa Minor, Polaris at handle base, Circumpolar

Ursa Major, big dipper, Mizar and and alcur

Ursa Major, big dipper, Mizar and and alcur

Cassiopeia the queen, W shape, Circumpolar

Cassiopeia the queen, W shape, Circumpolar

Orion, Winter constellation, orion’s belt, Betelgeuse on arm & Rigel on bottom right leg

Orion, Winter constellation, orion’s belt, Betelgeuse on arm & Rigel on bottom right leg

What is Dead Reakoning

Using known speed and direction to roughly approximate your location

How can latitude be determined

Based on the altitude of the North celestial pole. look for Polaris

How can Longitude be determined?

Compare location and local time of an object to the prime meridian.

What are the 7 ancient planets?

Moon, Mars, Mercury, Jupiter, Venus, Saturn, Sun

Where does the Month come from?

The lunar cycle, 29.53 days

Where does the year come from?

Orbit of the earth, 365.24 days

Julian calendar

Julius cesar calendar, added 10 days and every 4 years leap year to reach 365.25

Gregorian calendar reforms

Removed leap years from years that were a multiples of 4, 100, or 400

Common solutions to the Calendar problem

Don’t count some days, Very the length of months and the year, Accept drift against seasonal markers

Solar Day

Time it takes for the sun to return to it’s place in sky, 24 hours, 4 min longer than sidereal bc of orbit

Sidereal day

Time it takes a star to return to its spot in the sky, just under 24 hrs

Explain sundails/Sunshadows

relate time to the sun based on shadows created. location dependent, Numen is pointed at the NCP and the surface is perpendicular.

Pendulum clock

Period of the pendulum is regular and regulated by the string, Very accurate

How are clocks used for navigation?

Comparing local time to time at a fixed point can determine longitude

How many degrees should be marked out for an equatorial sundial?

15

What factors influence planet brightness?

Their size and proximity to the earth and sun

Spico theories

Developed geocentrism

Copernicus theories

Published heliocentrism, Described retrograde observations

Tycho and Sophie Brahe

took precise and extensive measurements of the sky. Didnt share them

Kepler

Used tycho and Brahe measurements to develop the 3 laws of planetary motion

3 laws of planetary motion?

1. Orbits are elipses

2. equal areas

3. p squared = a cubed (period of orbit is proportional to its area)

William Herchel

Discovered Uranus using a telescope

Neptune’s discovery

Large telescopes and measurements showed gravitational effects on Uranus orbit and predicted the location of Neptune

Pluto’s Discovery

Same as Neptune’s Clyde Tombaugh

Why isn’t pluto a planet?

Much smaller than predicted and smaller than other planets,

It’s orbit isn’t planar with the other planet’s

Other far solar system object were discovered

Many icy objects were in pluto’s orbit