“Photosynthesis converts carbon dioxide and water into oxygen and glucose. Glucose is used as food by the plant and oxygen is a by-product. Cellular respiration converts oxygen and glucose into water and carbon dioxide. Water and carbon dioxide are by- products and ATP is energy that is transformed from the process.”
The light-dark cycle caused by the rising and setting of the sun is responsible for what are called circadian rhythms. These are biological processes that show a cycle of around 24 hours, the time between consecutive rising of the sun. Experiments have shown that without the external cue of sunlight, the circadian rhythms of organisms tend to break down. These can be reset by being re-exposed to these cues. Jet lag is due in part to a re-setting of the circadian rhythm, as you travel to a different time zone, your body has to become used to a different timing of night and day. <span> </span>
They use radiometry and pyrometry
NASA uses the Transiting Exoplanet Survey Satelite (TESS) telescope that employes this technology
This telescope measures the brightness/luminosity of stars. When this brightness drops regularly, every more or less in the same number of years, then there is the likelihood of a planet orbiting the star. The dip in brightness of the star is directly proportional to the size of the planet and the distance between the star and the orbiting planet.