Astronomers use earth-based spectroscopy

In summary, astronomers use earth-based spectroscopy to determine the chemical composition of nebulae, stars, planets, etc. by analyzing the light that passes through the Earth's atmosphere. There are potential problems with the Earth's atmosphere, such as absorption by the same atoms and background interference, but these can be mitigated by using high resolution spectra and working between the lines in the atmosphere. Infrared wavelengths can be particularly challenging due to the brightness of the sky, but space-based telescopes can help with calibration and background subtraction. Overall, spectroscopy is a reliable method for determining chemical composition in the universe.
  • #1
AdkinsJr
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How can astronomers use earth-based spectroscopy to determine the chemical composition of nebulae, stars, planets etc. when the light has to pass through the Earth's atmosphere before it's detected? Does the chemical composition of the Earth's atmosphere pose a problem?
 
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  • #2


Not much of one - there are two possible problems

The spectral line being absorbed by the same atom in the Earth's atmosphere. In the visible band the atmosphere is relatively thin compared to a star and most of the elements found in a star are rare. So very little of a hydrogen line from the sun would be absorbed.
This isn't true for high energy lines in the ultra violet which can be absorbed which is why UV telescopes have to go in space.

The background from the same line (or something at the same wavelength) is also a problem. But since the lines in the visible are very narrow, with a high resolution spectra you can work between the lines in the atmopshere. This is a big problem in the near IR because the O-H bond in water has 1000s of emission lines which make the sky very bright and it's difficult to work between them. At longer infrared wavelengths the blackbody emission from the atmopshere swamps all the lines an you have to go into space.
 
  • #3


Should they use reference? The resulted spectrum is the subtraction of the light beam from the star (planet etc) and the blank
 
  • #4


Not generally for spectra.
The emission lines in the atmosphere are strong enough that if they occur on top of a line from a star you aren't going to easily subtract them. Also spectra of anything faint take a long time to measure an the sky brightness can change on much shorter timescales.

In the far-IR and microwave the sky is brighter than the source and you o have to do complex background subtraction to see anything at all.
 
  • #5


Space based telescopes are also used for spectroscopy so calibration is not an issue. If you are asking if spectroscopy could be suspect, the answer is no.
 

Related to Astronomers use earth-based spectroscopy

1. What is earth-based spectroscopy?

Earth-based spectroscopy is a technique used by astronomers to analyze the light emitted or reflected by objects in space. It involves studying the spectrum of electromagnetic radiation, which can provide information about an object's composition, temperature, and motion.

2. How does earth-based spectroscopy work?

Earth-based spectroscopy works by collecting the light from a celestial object using a telescope and then passing it through a device called a spectrometer. The spectrometer separates the light into its component wavelengths, creating a spectrum. By analyzing the spectrum, astronomers can determine the chemical elements present in the object and their relative abundance, as well as other characteristics.

3. What can earth-based spectroscopy tell us about celestial objects?

Earth-based spectroscopy can tell us a lot about celestial objects. It can provide information about their chemical composition, temperature, density, and motion. It can also reveal the presence of molecules, such as water and carbon dioxide, in an object's atmosphere. Spectroscopy can also be used to study the physical conditions within stars and galaxies.

4. What are the advantages of using earth-based spectroscopy?

The main advantage of earth-based spectroscopy is that it allows astronomers to study a wide range of celestial objects, from planets and moons in our own solar system to distant galaxies and quasars. Another advantage is that it is a non-invasive technique, meaning it does not require physical contact with the object being studied. This allows for the study of objects that are too far away or too dangerous for humans to reach.

5. Are there any limitations to earth-based spectroscopy?

Yes, there are some limitations to earth-based spectroscopy. The Earth's atmosphere can interfere with the light being observed, especially in certain wavelengths. This can be overcome by using specialized filters and instruments, but it can still limit the accuracy of the data collected. Additionally, earth-based spectroscopy is limited by the size and capabilities of the telescopes and spectrometers being used. To study more distant and faint objects, astronomers often need to use space-based spectroscopy techniques.

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