1.2.3 The Beginning of Astrophysics

The Beginning of Astrophysics
1.2.3

By Caitlin Ford

Objectives

- summarize the development of the telescope

- identify the recent developments in astronomy and their role in providing a better understanding of the universe

- describe Albert Einstein's theories

- explain Hawking radiation

Astronomy and the Modern Era

The "modern era" is 1400s-now. Astronomy continued to evolve with the development of telescopes and knowledge of the universe expanded.

Astrophysics was born - a branch of astronomy that studies the physical properties of celestial objects.

Astrophysics

Theoretical Astrophysics - creating models without making observations of the universe. Isaac Newton was a theoretical astrophysicist.

Observational Astrophysics - using telescopes and other equipment to observe the universe. Data observed is given to theoretical astrophysicists to change their models.

Evolution of Telescopes

Telescopes started as a tube with two lenses. Now, a lot of telescopes use mirrors and are launched into space to avoid atmospheric interference and light pollution.

A newer telescope allowed Uranus and its moons to be discovered by William Herschel! He wanted to call the planet Georgium Sidus (after the current king) but was eventually changed.

Dropdown

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Select answer

astrophysics includes making models of the universe without making observations.

Edwin Hubble

Edwin Hubble discovered that many galaxies lie beyond the Milky Way and the universe is expanding at a constant rate.

Pointed the largest telescope of the time (1923) at a hazy patch of sky and discovered the Andromeda galaxy.

An Expanding Universe

Hubble discovered that light coming from the galaxies he studied appeared to shift toward the red end of the spectrum.

Doppler Effect - the decrease in pitch or frequency of sound, light, or other waves as the source of the wave moves away (think of a train or motorcycle whizzing past you!)

A light source moving towards you shifts toward the blue end of the spectrum. A light source moving away from you shifts toward the red end of the spectrum.

Hubble's Law

Hubble's Law - Galaxies are moving away from each other at a rate constant to the distance between them. The farther away a galaxy is, the faster it recedes.

Labelling

Which scientist discovered the planet Uranus and its moons?

Drag labels to their correct position on the image

Galileo Galilei

Johannes Kepler

Edwin Hubble

William Herschel

Albert Einstein

Theory of Relativity - describes the relationship between space and time.

General Theory of Relativity - Gravity warps space. The more mass an object has, the more it warps space. The Sun is massive enough to warp space throughout the solar system. As a result, everything in the solar system orbits the Sun in curved paths. 

General Theory of Relativity

Without gravity, a light beam travels in a straight line. But, as the light passes an object with a lot of mass, gravity warps space and bends the light beam.

Stephen Hawking

He was best known for his work on black holes - a super-massive dead star forming a space region where gravity is so strong that even light cannot escape.

Hawking radiation - this is spontaneously emitted by black holes.

Multiple Choice

Look at this photo. If an object is blue shifted, what does that mean?

• It is moving towards you.

• It is moving away from you.

• It is staying still.

Drag and Drop

Hawking radiation is spontaneously emitted by​

Placeholder

Drag these tiles and drop them in the correct blank above

black holes.

exoplanets.

neutron stars.

galaxies.

Match

Match the scientist with their contribution.

• Stephen Hawking

• Edwin Hubble

• Albert Einstein

• William Herschel

predicted black hole radiation

discovered Andromeda galaxy

postulated the theory of relativity

discovered the planet Uranus

• predicted black hole radiation

• discovered Andromeda galaxy

• postulated the theory of relativity

• discovered the planet Uranus

Great Job!

Today, you learned:

- the development of the telescope

- the recent developments in astronomy and their role in providing a better understanding of the universe

- Albert Einstein's theories

- Hawking radiation.