Here's why:
* Hydrogen's atomic structure: The spectral lines of an element are determined by the energy levels within its atoms. Hydrogen has a simple atomic structure with only one proton and one electron. The specific transitions between energy levels in hydrogen are always the same, regardless of its location.
* Universal nature of spectral lines: Spectral lines are a fundamental property of elements and are not influenced by the environment or location. The same lines are observed in laboratories on Earth, in the Sun, in distant stars, and even in distant galaxies.
However, there are some differences in how the lines appear:
* Doppler shift: The movement of a star or planet relative to Earth causes a shift in the spectral lines. This Doppler shift can be used to determine the object's velocity towards or away from us.
* Line broadening: The width of spectral lines can be affected by the temperature, pressure, and density of the gas. For example, hydrogen lines in the Sun's atmosphere will be broadened due to the high temperature and pressure.
In summary: The spectral lines of hydrogen are the same for all celestial objects, but their exact position and width can vary due to factors like Doppler shift and line broadening.
