Astronomy Practice Exam 2026 – Complete Preparation Guide

The primary composition of solar prominences is glowing hydrogen, which plays a crucial role in their structure and appearance. Solar prominences are massive, bright features extending outward from the Sun's surface, supported by magnetic fields. They consist primarily of plasma, which is a state of matter similar to gas but consists of charged particles, predominantly hydrogen ions and electrons.

In these prominences, the hydrogen gas is heated to high temperatures, causing it to become ionized and emit light. This process makes hydrogen the dominant element observed within these structures. The presence of hydrogen is essential, as it is the most abundant element in the Sun and overall in the universe, significantly influencing the behavior of solar phenomena.

The other options, while they represent elements found in various astronomical contexts, do not account for the primary composition of solar prominences. Carbon dioxide and oxygen, for instance, exist in trace amounts in the solar atmosphere but are not the main constituents of prominences. Helium, although it is present in the Sun and responsible for some of the energy generation processes occurring through nuclear fusion, does not make up the bulk of what is seen in solar prominences. Thus, glowing hydrogen stands out as the correct answer in this context.