Chapter 3 Flashcards
What is the Big Bang Theory?
A concept that the universe emerged from a single dense, hot state 14 billion years ago. The universe is currently 20 light-years across and will either continue expanding or collapse in on itself, depending on average density matter and energy within.
What is the evidence for the Big Bang Theory?
- distant star clusters moving away at greater speeds than closer ones
- amount of cosmic microwave background radiation is uniform throughout the universe, which implies it represents leftover energy from an early period of expansion
How many galaxies are in the universe and which are we in?
The universe contains 50 billion galaxies. We live in the Milky Way with 400 billion stars - it is a typical spiral galaxy consisting of a bright central region with a high density of stars & a flat circular region containing most of the other stars. Younger & brighter stars form in long spiral arms that extend out from the galactic centre, our solar system lies in one of these spiral arms.
How is our solar system structured?
8 planets orbit the sun, most of which are too far or too close to habit life. Earth is the 3rd planet and is the perfect distance of orbit for supporting life.
What are terrestrial planets vs jovian planets?
Terrestrial planets have solid surfaces and are relatively small in size & mass. Earth, Mercury, Venus and Mars.
Jovian planets are much larger and made up of gases. They tend to have rings around them and also have more moons. Jupiter, Saturn, Uranus, Neptune.
What is the shape of the Earth?
Not a perfect sphere, it bulges slightly at the equator and is flattened somewhat at the poles (an oblate spheroid). Circumference at equator=40075km vs poles=40008km.
What causes the Earth’s shape?
The bulge at the equator is caused by the centrifugal force of the Earth’s rotation and by the different densities of the Earth’s crust & gravitational field.
How does Earth receive solar radiation?
Earth has a curved surface so the intensity of the arriving sun rays varies by latitude.
What is the angle of incidence?
The angle at which the sun’s rays strike the Earth’s surface. High at low latitudes, becoming lower going toward the poles. Therefore solar energy is spread over larger surface areas at higher latitudes compared to the same amount received at a lower latitude. Incoming energy = low when angle of incidence = low (high lat.). Lower lat. = more intense solar radiation & higher angle of incidence (75-90) & solar radiation most direct.
How does Earth revolve around the sun?
Earth reloves around the sun (every 365 days) on an elliptical path and orbits counterclockwise relative to a view above the North Pole on a flat plane - the plane of the ecliptic. The sun is not located in the centre of orbit and the distance between Earth & sun varies over the course of the year.
What is perihelion?
Earth’s closet point to the sun (January) 147 mill km
What is aphelion?
Earth’s furthest point from the sun (July) 152 mill km
Earth’s Rotation and Axial Tilt
As Earth revolves around the sun it rotates counterclockwise (24h for 1 rotation) on its axis (imaginary line pole to pole). The axis of Earth is an important reference point as it is 23.5 degrees from a line perpendicular to the plane of the ecliptic (maintaining this degree all year) and is the reason for the reasons.
What is the circle of illumination?
The great circle on Earth that borders day and night and moves as the Earth rotates.
Time Zones
24 time zones
15 degrees each
Each TZ is 7.5 degrees east and west of its meridian
Prime Meridian is the Standard - UTC system calculated as # of hours ahead or behind the Prime Meridian
