Nebula 09/10/24

What is a nebula?

Birthplace of stars, often formed after a star explodes.

What did astronomers initially think about nebulae?

They belived that they were within our galaxy.

What was Edwin Hubble’s key contrubution?

Hubble proved that there are more galaxies beyond the Milky way, showing that Milkey way is not the entire universe.

Where was Hubble working during his discoveries?

Mt. Wilson Observatory

What did Hubble observe about the brightest nebulae?

They were found in the Andromeda galaxy.

Who was Henrietta Leavitt, and what challege was she adressing?

Leavitt was an American Astronomer working on the problem of dertmining distances to objects in space.

What did Henrietta Leavitt discover about the Cepheid variables?

The brightness of the Cepheid variables is directly releated to their period, providing a way to measure distances in space.

Why was Leavitt’s work significant to Hubble?

Her discoveries solved Hubble’s problem of determining the distance to other galaxies.

What is red shift, and what does it indicate?

Redshift occurs when light from a galaxy shifts towards the red part of the spectrub, indicating the galaxy is moving away.

What did Hubble discover about the galaxy movement in 1929?

The further a galazy is, the faster it is moving away, proving that the universe is EXPANDING.

What was George Lemaitre’s theory in 1929?

He proposed that all matter in the universe was once compacted into a “primodial atom” which expanded to form the universe.

How did Lemaitre’s work connect to Einstein’s theories?

It was based on Einstein’s theory of general relativity.

Who contributed to developing the Big Bang Theory with nuclear physics?

George Gamov and R.Alpher

What prediction did Gamov and Alpher make about the Big Bang?

The Big Bang would leave behind heat radiation, now observable as cosmic microwave background radiation.

Who discovered the cosmic background raditation in the 1960’s and where?

Arno Penzias and R. Wilson at Bell Labs in New Jersey.

What was the observed temperature of the cosmic background radiation?

Approximately 4 kelvin, close to the predicted 5 Kelvin.

What does the Steady State Theory propose?

The universe is infinitely old, infinitely large, and constantly creates new matter, so it has no origin.

Who was the main proponent of the Steady State Theory?

F. Hoyle

What did Steven Hawking and R.Penrose contribute to black hold physics?

They described singulatires, where a star’s entire mass collapses into the size of a proton at the center of a black hole.

How does the Big Bang theory relate to singulatiries?

Hawking and Penrose applied Big Bang Theory concepts to their research on singularities.

What did Vera Rubin discover about galaxies?

She found evidence for dark matter, proving that there must be more mass in the galaxy that doesn’t emit light.