Question

Rank these descriptions of a stellar spectrum in chronological order from earliest to latest as it travels from a star through the interstellar medium to an observer on the Earth.

A continuous spectrum of white light is emitted____
The observer measures a star as redder than it really is____
An observation of a star's spectrum or image is made____
Light enters a dust cloud____
Blue and violet light is absorbed or scattered____

Answer 1

Starlight from a star to Earth goes through stages where a continuous spectrum is emitted, interacts with interstellar dust leading to the absorption and scattering of blue and violet light, and finally appears redder to an observer, culminating in the analysis of its spectrum.

Step-by-step explanation:

The question asks to rank descriptions of a stellar spectrum from earliest to latest as it travels from a star through the interstellar medium to an observer on Earth. The order, following the journey of starlight, is as follows:

1. A continuous spectrum of white light is emitted.
2. Light enters a dust cloud.
3. Blue and violet light is absorbed or scattered.
4. The observer measures a star as redder than it really is.
5. An observation of a star's spectrum or image is made.

When light from a star passes through an interstellar dust cloud, shorter wavelengths of light such as blue and violet are more likely to be scattered or absorbed, a process known as interstellar reddening. This causes the observed starlight to appear redder than it is, a consequence of the Doppler effect. When the light finally reaches an observer on Earth, a spectroscopic analysis may reveal an absorption spectrum with characteristics indicating that interstellar dust has affected the light.