Final answer:
NASA knows the types of elements that make up planets and stars through spectroscopic analysis and theories of nucleosynthesis, allowing them to identify the elements and predict their abundance.
Step-by-step explanation:
Understanding Celestial Chemistry
Astronomers and physicists have utilized laboratories on Earth to break down the components of light to discover how atoms absorb and emit light. By understanding spectroscopic analysis, scientists are able to detect the specific lines that correspond to each element, which in turn has unveiled the types of elements that compose celestial bodies. This is crucial in determining the potential of various worlds for supporting life or for being similar to our own planet.
We know that the formation and composition of planets can tell us about their origins. Take, for instance, the Sun, Jupiter, and Saturn, which share a hydrogen-dominated composition, implying a common material reservoir. Contrastingly, terrestrial planets like Earth mainly comprise heavier elements such as iron and silicon due to the loss of lighter materials during the planet formation process in the inner solar system.
Discoveries in nucleosynthesis have indicated that stars are the alchemists of the cosmos, fusing simpler elements into the complex, diverse chemicals found on Earth and beyond. These nuclear reactions within stars allow scientists to predict the abundance of elements across different environments, explaining the prevalence of certain elements and the rarity of others.