Rainbows from Space

Astronomer’s Tools Telescopes Telescopes –On Earth or in Earth orbit Cameras Cameras Prisms (spectroscope) Prisms (spectroscope) Photometer (measures brightness) Photometer (measures brightness) Computer Computer

Orion Nebula

Eagle Nebula

Crab Nebula

Light from space Because most objects in space are too far away to visit, examining their light is the only tool we have to explore them. Because most objects in space are too far away to visit, examining their light is the only tool we have to explore them. Distance, temperature, composition, and motion details are a few of the things we can deduce from their light. Distance, temperature, composition, and motion details are a few of the things we can deduce from their light.

Spectroscopy A close up look at the color of light White light is a mixture of all the colors. White light is a mixture of all the colors. Isaac Newton showed that a prism can show the colors that make up white light. Isaac Newton showed that a prism can show the colors that make up white light. Isaac Newton born: December 25, 1642 Woolsthorpe, England died: March 20, 1727

White light is composed of many colors Newton passed sunlight through a piece of glass called a PRISM, and produced colors. Newton passed sunlight through a piece of glass called a PRISM, and produced colors. He called these colors the spectrum, from the word spectre, meaning ghost. He called these colors the spectrum, from the word spectre, meaning ghost.

Rainbow A Rainbow is formed when sunlight passes through raindrops, which act like little prisms. A Rainbow is formed when sunlight passes through raindrops, which act like little prisms.

Spectroscope Today astronomers use very accurate prisms, called spectroscopes, to find out about objects in space. Today astronomers use very accurate prisms, called spectroscopes, to find out about objects in space.

Personal Spectroscope Astronomers’ spectroscopes are quite elaborate, but simple spectroscopes are cheap and easy to use. Astronomers’ spectroscopes are quite elaborate, but simple spectroscopes are cheap and easy to use. Many spectroscopes use a grating, a piece of plastic or glass with thousands of lines scratched in it. Many spectroscopes use a grating, a piece of plastic or glass with thousands of lines scratched in it.

Observing Spectra Look at a white light bulb with the diffraction grating and see the colors – like a rainbow. Look at a white light bulb with the diffraction grating and see the colors – like a rainbow.

Glowing Gases View the gas tubes. View the gas tubes. Every glowing gas has a unique pattern of colors, like a fingerprint is unique to a person. Every glowing gas has a unique pattern of colors, like a fingerprint is unique to a person. Record the colors you see for each gas Record the colors you see for each gas

Gas Tube Spectra Hydrogen Hydrogen Helium Helium Neon Neon Oxygen Oxygen Mercury Mercury

Mystery Gas View the mystery gas and record its pattern of colors. View the mystery gas and record its pattern of colors. Now refer to your drawings of the other gasses and see if you can recognize any of the line patterns. Now refer to your drawings of the other gasses and see if you can recognize any of the line patterns. Can YOU tell what the gas in the mystery tube is? Can YOU tell what the gas in the mystery tube is?

Pleiades

Horsehead Nebula

Bright and Dark Spectra Clouds of glowing gas show bright lines Clouds of glowing gas show bright lines High pressure glowing gas shows continuous colors High pressure glowing gas shows continuous colors Light from high pressure gas passing through cooler gas gives dark lines Light from high pressure gas passing through cooler gas gives dark lines

The Sun’s Spectrum By passing sunlight through a spectroscope we can determine all of the chemical elements that make up the Sun. By passing sunlight through a spectroscope we can determine all of the chemical elements that make up the Sun.

What’s the Sun made of? By matching the dark lines in the Sun’s spectrum with lines observed of elements in a laboratory you can determine what elements are present. By matching the dark lines in the Sun’s spectrum with lines observed of elements in a laboratory you can determine what elements are present.

Solar Spectrum

Doppler Effect Christian Doppler first showed that when a source of light or sound is coming towards you or going away, the color or pitch of the light or sound is raised or lowered. Christian Doppler first showed that when a source of light or sound is coming towards you or going away, the color or pitch of the light or sound is raised or lowered. Christian Doppler born: 29 November 1803 Salzburg, Austria died: March 17, 1853

Sound When a source of sound is coming toward the observer, the pitch of the sound is raised. When a source of sound is coming toward the observer, the pitch of the sound is raised. When a source of sound is going away from the observer the pitch is lowered. When a source of sound is going away from the observer the pitch is lowered.

Sound is a vibration Sound vibrations travel through air like waves in the ocean Sound vibrations travel through air like waves in the ocean

Doppler Effect Demo Sounder first comes toward you, then moves away. Sounder first comes toward you, then moves away. The pitch will be higher when coming toward you, and lower going away. The pitch will be higher when coming toward you, and lower going away. Sounder coming toward you – higher pitch Sounder moving away from you – lower pitch

Why? Sound vibrations travel through air outward from the source. Sound vibrations travel through air outward from the source. When the sound source is moving the waves bunch up, or stretch out. When the sound source is moving the waves bunch up, or stretch out. Low pitched SoundHigh pitched Sound Observer here hears higher pitch Observer here hears lower pitch

Light When a source of light is coming toward the observer, the color of the sound is made bluer. When a source of light is coming toward the observer, the color of the sound is made bluer. When a source of light is going away from the observer the color is reddened. When a source of light is going away from the observer the color is reddened.

Doppler Effect on Light If the line pattern is shifted to the blue end the source is coming towards us. If the line pattern is shifted to the blue end the source is coming towards us. If shifted to the red end, it is moving away. If shifted to the red end, it is moving away.

Using the Doppler Effect to Detect an Unseen Planet If a star has a planet orbiting it, the planet will tug on the star due to its gravity. If a star has a planet orbiting it, the planet will tug on the star due to its gravity. As the planet orbits the star it will tug first on one side of the star, then on the other. As the planet orbits the star it will tug first on one side of the star, then on the other. gravity

Detecting a planet So the star first moves toward us, then away. So the star first moves toward us, then away. When moving towards us the spectrum will be a tiny bit bluer, and redder when moving away. When moving towards us the spectrum will be a tiny bit bluer, and redder when moving away. Unseen planet’s orbit

Lots of Planets Found The number of Extra-Solar planets discovered is now over 150 and growing every month. The number of Extra-Solar planets discovered is now over 150 and growing every month.

Artist’s Conception of 6-8 Earth Mass Planet Orbiting Star Gliese 876