The Sun is by far the brightest object in the sky, with an of −26.74. This is about 13 billion times brighter than the next brightest star, , which has an apparent magnitude of −1.46. The mean distance of the Sun's center to Earth's center is approximately 1 (about 150,000,000 km; 93,000,000 mi), though the distance varies as Earth moves from in January to in July. At this average distance, light travels from the Sun's horizon to Earth's horizon in about 8 minutes and 19 seconds, while light from the closest points of the Sun and Earth takes about two seconds less. The energy of this supports almost all life on Earth by , and drives and weather.
Neutrinos are also released by the fusion reactions in the core, but, unlike photons, they rarely interact with matter, so almost all are able to escape the Sun immediately. For many years measurements of the number of neutrinos produced in the Sun were by a factor of 3. This discrepancy was resolved in 2001 through the discovery of the effects of : the Sun emits the number of neutrinos predicted by the , but neutrino detectors were missing of them because the neutrinos had changed by the time they were detected.
David: We're better prepared now than we have been, but our technology is more sensitive to the effects of solar storms. We have two satellites, ACE and WIND, that are a million miles upstream in the solar wind and provide us with about a one-hour advanced warning of the magnetized clouds of material blown off of the sun by solar flares. This is enough to allow satellite operators and electrical power distributors to adjust equipment in anticipation of the impending impact.