Question

Based on what you know about Kirchhoff’s laws of spectroscopy, explain how the Sun’s light can be reflected off a planet’s surface to give astronomers information about the chemical composition of its atmosphere, even though the planet itself is not creating this light. What type of spectrum will this produce (continuous, absorption, or emission)?

Answer 1

The spectrum of any object is the variation in the intensity of its radiation at different wavelengths.

Objects having different temperatures and compositions emit different types of spectra. Upon observing an object's spectrum, astronomers can figure out its temperature, composition and physical conditions, among other things.

Kirchhoff's Laws are:

1.A hot object whether solid, liquid or gas, under high pressure, gives off a continuous spectrum.

2.A hot gas under low pressure produces a bright-line or emission line spectrum.

3.A dark line or absorption line spectrum is seen when a source of a continuous spectrum is viewed behind a cool gas under pressure.

4. The wavelength of the emission or absorption lines depends on what atoms are molecules are found in the object under observation.