Unit 1: Space Exploration Flashcards
What is the difference between Solstices and Equinoxes
Solstices:
- 16 or 8 hours of night and day respectively
- June 21 and December 21.
- Summer and winter
Equinoxes:
- March 12 and September 22
- Equal amounts of day and night
- Spring and fall
Explain the two Models of Planetary Motion
Geocentric:
- 2000 years ago, Aristotle
- Earth at the centre with planets and stars rotating around
Heliocentric:
- 1530, Nicolas Copernicus, circular motion
- Sun at the centre
- Kepler, orbits are actually ellipses
Explain the two units used to measure distance in space
Astronomical Units (AU): - distance from centre of the earth to centre of the sun
Light Years:
- 9.5 trillion km
- Distance light travels in a year
- light travels 300 000 km/s
What are the Early Astronomers Tools
Quadrant - Star’s height above the horizon
Astrolabe - Accurate star charts
Cross-staff - Accurate star charts
Telescope - invented in the 16th century
What is the composition of a Star
75% hydrogen
23% helium
2% oxygen, nitrogen, carbon, silica dust
How is a Star Born
- Gravity form gas and grains of dust into small rotating cloud
- Core become hot, becomes a protostar that begins to glow
- Fusion begins with hydrogen turning to helium when core reaches 10 mill C
How does a Star Die
- Hydrogen is used up, star shrinks
- Gravity contract the star, nuclear reactions begin and cause outer layers to expand, becomes Red (Super)Giant
- Fusion reaction stops
Death of Sun-like stars or Red Giants
- core temperature lowers and fusion stops
- gravity collapses the star
- star shrinks
- white dwarf, begins to fade to black dwarf
Death of Massive Stars or Red Supergiants
- Reaction stops when out of fuel
- gravity collapses the star
- collapse ends with shockwave
- outer layers explode, supernova
- core becomes neutron star or black hole
Black Hole - Dense star ruminant, strong gravity
Neutron star - Rapidly spinning, 30 km diameter
Hertzsprung-Russell Diagram (H-R)
- created in 1910
- dots correspond to stars luminosity and temperature
- y-axis is luminosity
- x-axis is stars surface temp (reversed, hotter is on the left)
Constellations
- groupings of stars in patterns
- 88 recognized
- unofficial patterns are asterisms
Galaxies
- Group of millions or billions of stars (gas and dust)
- Held together by gravity
Types - Spiral, Elliptical, Irregular
Protoplanet Hypothesis
Formation of our solar system
- Gas and dust begins swirling
- Most material forms sun
- The rest forms planets
Our Sun
- 100x wider than earth
- Surface temp 5 500 C
- Core temp 15mil C
- Solar wind, charged particles, pass earth at 400 km/s
- Earth protected by magnetic field
Name and Compare the two types of Planets
Inner or terrestrial
- small, rocky
- closer to the sun
Outer or jovian
- larger, gaseous
- farther from the sun