Astrophysics and Cosmology How do we know what we know about the universe around us?

The farthest from the Earth we have been to return “direct evidence” has been Mars Astrophysics and Cosmology

How do we know what we know about the universe around us? The farthest from the Earth we have been to return “direct evidence” has been Mars The rest of the universe is understood by “looking” that is, by the collection of electromagnetic waves Astrophysics and Cosmology

Tools: Telescopes – can receive information both inside and outside of the visible window Astrophysics and Cosmology

Tools: Telescopes – can receive information both inside and outside of the visible window Most of what is in the (currently) observable is gaseous. Astrophysics and Cosmology

Tools: Telescopes – can receive information both inside and outside of the visible window Most of what is in the (currently) observable is gaseous. Spectroscopic analysis of emission and absorption spectra most common tool Astrophysics and Cosmology

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Astrophysics and Cosmology

Moving one step closer to finding the fingerprints of life in a habitable planet beyond the solar system, astronomers have for the first time detected carbon dioxide in the atmosphere of a planet that orbits a star other than the sun Fall 2008

Moving one step closer to finding the fingerprints of life in a habitable planet beyond the solar system, astronomers have for the first time detected carbon dioxide in the atmosphere of a planet that orbits a star other than the sun Fall 2008 How on Earth do they know this??????

Astrophysics and Cosmology The Universe contains vast amount of hydrogen. Other elements are being synthesized Complex molecules are also being synthesized in gas clouds

Astrophysics and Cosmology A strange observation: When spectra were first collected about the universe, there were no known fingerprints that matched what was observed.

Astrophysics and Cosmology A strange observation: When spectra were first collected about the universe, there were no known fingerprints that matched what was observed. ?

Astrophysics and Cosmology A strange observation: When spectra were first collected about the universe, there were no known fingerprints that matched what was observed. It was realized that the spectra fit known elements, but that all of the wavelengths in the spectra had been “shifted” to longer wavelengths

Astrophysics and Cosmology The Red and Blue Shift

Astrophysics and Cosmology The Red and Blue Shift

Astrophysics and Cosmology The Red and Blue Shift The Wavelengths are the same in all directions only if the atoms in the gas are not moving.

Astrophysics and Cosmology The Red and Blue Shift The Wavelengths get “squished” in the direction of motion, and “stretched” in the opposite direction.

Astrophysics and Cosmology The Red and Blue Shift The Wavelengths get “squished” in the direction of motion, and “stretched” in the opposite direction.

Astrophysics and Cosmology It was further observed that ALL spectra form ALL deep space objects were shifted toward the red, ie, longer wavelengths The implications is that ALL objects in the universe, on the average, are moving away from the Earth.

Astrophysics and Cosmology The only way ALL objects in the universe can be moving away from the Earth is if the universe is expanding.

Astrophysics and Cosmology Expanding FROM where and TO where? ? ?

Astrophysics and Cosmology The Big Bang The universe exploded into existence approximately 15 billion years ago (the Big Bang). Shortly after the Big Bang, the hydrogen that makes up the current universe was formed. Other elements were subsequently synthesized from the hydrogen. All of the material in the universe (including you) is 15 billion years old.