Show Menu
Cheatography
  1. Home >
  2. Education >

AST1631 - Introduction to Astronomy Cheat Sheet (DRAFT) by

Discuss various astronomical concepts, including the solar system, stars, galaxies, and cosmology. They also detail specific information about planets like Venus and Mars, different types of stars like white dwarfs and neutron stars, and celestial objects like asteroids and comets. There is also content about the Milky Way galaxy and the Big Bang theory.

This is a draft cheat sheet. It is a work in progress and is not finished yet.

A Century of Astronomy

 
1920's
Edwin Hubble determines that Andromeda Nedula is a galaxy.
 
Cecilia Payne-­Gap­oshkin determines that hydrogen is the most common element in the universe.
 
Hubble discovers expanding universe.
1930's
Clyde Tombaugh discovers Pluto (planet).
 
Karl Jansky detects first radio waves from space.
 
Walter Baade & Fritz Zwicky describe neutron stars that would form in a supernova collapse.
 
Hans Bethe describes nuclear fusion that powers stars.
1940's
Palomar 200 inch telescope built.
1950's
Sputnik 1 launched - 1st man made object in space.
 
Luna 2 & 3 explore the moon (crash into and photog­raphing the dark side).
1960's
1st Human to orbit Earth.
 
Mariner 2 became first man made object to visit another planet (Venus).
 
Maarten Schmidt discovers quasars (active galaxies) and therefor the most distance objects know at that time.
 
Arno Penzias & Robert Wilson discovers the Cosmic Microwave Backround.
 
Luna 9 made the 1st soft landing on the moon.
 
Jocelyn Bell discovers the 1st pulsar.
 
First manned flight to the moon (Apollo 8).
 
First manned landing on the moon (Apollo 11).
 
Charles Thomas Bolton identified Cygnus X-1 as a black hole
1970's
Uhuru is the 1st satellite launched.
 
1st Space station launched.
 
Verena 9 sends back 1st images from the surface of Venus.
 
Viking landers arrive at Mars to search for life.
 
Voyager 1 & 2 launched to explore outer solar system.
 
Rings of Uranus discov­ered.
 
Vera Rubin confirmed the existence of dark matter.
1980's
IRAS launched and become 1st satellite to work in infrared.
 
Voyager 2 visits Uranus.
 
Voyager 2 visits Neptune.
1990's
Magellan spacecraft maps the surface of Venus with radar.
 
Hubble Space Telescope launched.
 
Cosmic Background Explorer detects ripples in the background radiation.
 
!st confirmed detection of an exoplanet.
 
Constr­uction of ISS (Inter­nat­ional Space Station) begins.
 
Discovery of dark energy.
2000's
Mike Brown discovers Eris in the outer solar system.
 
The Intern­ational Astron­omical Union formally defined a planet and dwarf planet.
2010's
Suvi Gezari discovers 1st visual proof of a black hole.
 
First Extrasolar asteroid discov­ered.
 
New Horizons explores Pluto
 
1st detection of gravit­ational waves.
 
Source of gravit­ational waves (neutron star collision) identi­fied.

The Celestial Sphere

Zenith
The point straight overhead of an observer.
Horizon
The circle where the celestial sphere meets the Earth.
Celestial pole
The projection of the Earth's poles to the celestial sphere.
Celestial equator
The projection of the Earth's equator to the celestial sphere.
Ecliptic
The apparent path of the Sun on the celestial sphere.
Vernal equinox
The inters­ection of the ecliptic and the celestial equator, where the Sun is moving northward.
Circum­polar stars
Stars close to the pole that never sets (e.g. Polaris).
Retrograde Motion
Only planets, the loop back wards when following the path of a planet.

Coordinate Systems

Locations on Earth
Latitude (north/ south) and Longitude (east/ west).
Location in the Sky
Declin­ation (north/ south of celestial equator) and Right Ascension (east of vernal equinox in hours).

Ancient Astronomy

Eudoxus (Geoce­ntric)
An early mode of the universe.
Aristotle (Geoce­ntric)
The Earth is round, circular orbits and uniform speed.
Eratos­henes
Measure circum­ference of Earth using shadows.
Arista­rchus (Helio­cen­tric)
Suggested that Sun is the center of the universe.
Hipparchus
Magnitudes (apparent brightness - 1 being the brightest and 6 the faintest) of stars and discovered precession (how the Earth spins and how the axis' direction changes).
Ptolemy (Geoce­ntric)
A mathem­atical model putting everything together called The Almagest.

The Origin of Modern Astronomy

The Copernican Revolution - 1st suggested by Arista­rchus.
Nicolaus Copernicus (1473 to 1543) suggested that Earth is a planet and completed helioc­entric model.
Helioc­entric model: sun at the center with Earth and other planets revolving around the Sun. It predicted parallax of stars (not detected until 1838) and simply explained retrograde motion.
Retrograde motion: apparent backwards motion of planets explained by epicycles in the geocentric model and relative motion in the helioc­entric model. Continued use of circular orbits caused the need of epicycles in a helioc­entric model as well to explain motion.
Galileo Galilee (1564 to 1642) 1st scientist to perform experi­ments and 1st to use telescope to observe the space and make predic­tions.
Observ­ations and Predic­tions: Sun rotation, Sun and moon spots, Venus orbits the Sun (shown by the phases of Venus), Jupiter has 4 satellites and the Milky Way.

Time and The Calendar

Day
Rotation of Earth.
Week
Seven objects that move among the stars (Sun, moon and 5 known planets).
Month (29.5 days)
Phases of the moon.
Year (365.24 days)
Revolution of Earth around the Sun.
Stonehenge
Alignments with rising/ setting of sun/ moon.
Mayans
Complex calendar based on Venus.
Chinese
12-year cycle of Jupiter leads to 12-year cycle of Chinese zodiac.
Julian
Differs actual year by 11 min. Added up to 10 days over a thousand years.
Gregorian
Dropped 10 days to fix from Julian calendar and added extra rules for leap years.
Leap year
Add and extra day every 4 years, except century years (ending in 00) had to be divisible by 400 to be a leap year.

Phases of the Moon and Tides

Waxing lunar phase (overhead before midnight)
More illumi­nated (right side) each day, moving towards a full moon.
Waning lunar phase (overhead after midnight)
Less illumi­nated (left side) each day, moving towards a new moon.
Synodic month
Cycle of lunar phases (29.5 days).
Sidereal month
Revolution of moon around the Earth (27.3 days).
New moon
Always in same direction as the Sun, rises and sets with the sun.
Crescent
Always close to the Sun in the sky, visible right before (after) sunrise (sunset)..
Quarter
Halfway around the sky from the Sun.
Gibbous
More than halfway around the sky from the Sun
Full
Opposite side from the Sun, rises and sets opposite the Sun
Tides
Caused by the Moon and Sun (diffe­rential gravit­ation force), a stronger force is acting on the side closest.
Spring Tides (New & full)
When the Sun and Moon are lined up and their forces are working constr­uct­ively to cause higher/ bigger tides.
Neap Tides (Quarters)
The forces caused by the Sun and Moon are working perpen­dicular destru­cti­vely) to each other.
Synchr­onous Rotation: The rotation and revolution of the moon are the exact same, causing the same side to always face Earth.

Eclipses

Solar eclipse
Moon pasees in front of the Sun with the same apparent size.
Lunar eclipse
Moon passes into the Earth's shadow (new moon).
Umbra
Darkest part, where the sunlight is completely blocked out.
Penumbra
Region of partial shadow, where the sunlight is partially blocked.
Total solar eclipse
The entire face of the sun is blocked out.
Partial solar eclipse
Part of the Sun's face is blocked.
Annular solar eclipse
A ring of sunlight is visible around the moon, when the moon is at a further point from Earth.
Total lunar eclipse
Entire moon in the umbra.
Partial lunar eclipse
Part of the moon in the umbra.
Penumbral lunar eclipse
Moon passes through the penumbra only.
Eclipse season
When the moon is near a node.
Saros Cycle
The time between very similar eclipses (18 years 11 days and 8 hours). .
 

Light and Electr­oma­gnetic Spectrum

Electr­oma­gnetic (EM) radiation
Created by moving photons (charged particle).
Wave nature
Wavele­ngth, frequency, interf­erence, reflec­tion, refrac­tion, diffra­ction and doppler effect.
Speed of light
300 000 km/s
Particle nature
Photoe­lectric effect and gravit­ational deflec­tion.
Temper­ature
Mausre of average kinetic energy of particles.
Absolute Zero
If there was absolutely no energy or movement.
Kelvin
Based on absolute zero = 0K = -273 degrees. Outer space is 3K.
Blackbody radiation
An ideal radiator that absorbs all radiation and only reflects light based on temper­ature.
Stefan­-Bo­ltzmann Law
Higher temper­ature means higher intensity.
Wien's Law
Higher temper­ature means shorter peak wavele­ngth.