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Flashcards in Chapter 8 Deck (24)
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1
Q

What is geometry?

A

It is the mathematics that describes the relationships of space, volumes, and areas

2
Q

What are the 5 axioms of geometry?

A

1) It is possible to draw a straight line from any given point to any other point
2) a straight line can go infinitely and still be straight
3) a circle can be described with any point as its centre and any distance as its radius
4) all right angles are equal
5) given a line and a point not on the line, only one line can be drawn through that point that will be parallel to the first line

3
Q

What does Euclidean geometry describe?

A

Flat spaces

4
Q

What is the great circle?

A

The line on a circle whose centre coincides with the centre of the sphere

On Earth, this is the equator

5
Q

How many great circles can there be on a sphere?

A

2

6
Q

How many times do thee great circles bisect?

A

Twice

7
Q

What is the issue with parallel lines on a sphere?

A

There are no possible parallel lines on the surface of a sphere.

8
Q

What can we change about Euclid’s original 5 postulates to define the geometry of a sphere?

A

Change the 5th postulate: that a parallel line is not possible on a sphere

9
Q

How many parallel lines can be drawn to another line from a given point?

A

An infinite number of lines

10
Q

What kind of dimensions do geometries come in?

A

Arbitrary shapes

11
Q

Name the 3 types of geometries

A

1) spherical
2) flat
3) hyperbolic

12
Q

What do all the types of geometry have in common?

A
  • they are all homogenous
  • ## they are all isotropic
13
Q

Why do hyperbolic geometries have a special role to play in our universe?

A

they are possible geometries for a homogenous and isotropic universe

14
Q

Why is the weakness of our local gravitational field problematic?

A

It makes it difficult to test General Relativity. We cannot automatically extrapolate the data for the stronger fields

15
Q

What is the nature of space time near a large object?

A

It is curved

16
Q

What was Arthur Eddington’s experiment?

A

He observed the stars close to the sun during a solar eclipse and compared them to their positions at night when they were not close to the Sun

17
Q

What was the result of Eddington’s Experiment?

A

The idea of light bending was consistent with the theory of general relativity

18
Q

How many arc seconds does the orbit of mercury change by every year?

A

5600

19
Q

How many of the arctics that the orbit of mercury changes by are accounted for by Newton’s Laws?

A

All but 43

20
Q

What explains the alteration in the varied arc seconds of Mercury’s orbit?

A

General relativity

21
Q

What is the alteration if Mercury’s orbit called?

A

the Perehelion of Mercury

22
Q

How has General Relativity helped with space technology?

A

It has allowed for accurate communication with spacecraft

EG Viking Lander could be located to within centimetres

23
Q

How can White Dwarves provide evidence of General Relativity?

A

The field of a WD is sufficiently strong to see gravitational redshifting in the photons that leave its surface

24
Q

What happens when 2 objects of great mass in orbit about one another lose energy?

A

They start to spiral until they collide with each other

This was predicted by GR