Earth orbit around the sun7/2/2023 The extremely stable fourth and fifth Lagrange points are in Earth’s orbital path around the Sun, 60 degrees ahead of and behind Earth. A satellite in this position would not be able to communicate with Earth. The third Lagrange point is opposite the Earth on the other side of the Sun so that the Sun is always between it and Earth. It is a good location for space telescopes, including the future James Webb Space Telescope (Hubble’s successor, scheduled to launch in 2014) and the current Wilkinson Microwave Anisotropy Probe (WMAP), used for studying the nature of the universe by mapping background microwave radiation. Since the Sun and Earth are in a single line, satellites at this location only need one heat shield to block heat and light from the Sun and Earth. Earth is always between the second Lagrange point and the Sun. The second Lagrange point is about the same distance from the Earth, but is located behind the Earth. The Solar and Heliospheric Observatory (SOHO), a NASA and European Space Agency satellite tasked to monitor the Sun, orbits the first Lagrange point, about 1.5 million kilometers away from Earth. The first Lagrange point is located between the Earth and the Sun, giving satellites at this point a constant view of the Sun. Satellites at the last two Lagrange points are more like a ball in a bowl: even if perturbed, they return to the Lagrange point. Satellites at these three points need constant adjustments to stay balanced and in place. A satellite at the other three points is like a ball balanced at the peak of a steep hill: any slight perturbation will push the satellite out of the Lagrange point like the ball rolling down the hill. Of the five Lagrange points in the Sun-Earth system, only the last two, called L4 and L5, are stable. Anything placed at these points will feel equally pulled toward the Earth and the Sun and will revolve with the Earth around the Sun. At the Lagrange points, the pull of gravity from the Earth cancels out the pull of gravity from the Sun. Other orbital “sweet spots,” just beyond high Earth orbit, are the Lagrange points. The GOES satellites carry a large contingent of “space weather” instruments that take images of the Sun and track magnetic and radiation levels in space around them. Built and launched by NASA and operated by the National Oceanic and Atmospheric Administration (NOAA), the GOES satellites provide a search and rescue beacon used to help locate ships and airplanes in distress.įinally, many high Earth orbiting satellites monitor solar activity. Every few minutes, geostationary satellites like the Geostationary Operational Environmental Satellite (GOES) satellites send information about clouds, water vapor, and wind, and this near-constant stream of information serves as the basis for most weather monitoring and forecasting.īecause geostationary satellites are always over a single location, they can also be useful for communication (phones, television, radio). When you log into your favorite weather web site and look at the satellite view of your hometown, the image you are seeing comes from a satellite in geostationary orbit. It is always directly over the same place on the Earth’s surface.Ī geostationary orbit is extremely valuable for weather monitoring because satellites in this orbit provide a constant view of the same surface area. This special, high Earth orbit is called geosynchronous.Ī satellite in a circular geosynchronous orbit directly over the equator (eccentricity and inclination at zero) will have a geostationary orbit that does not move at all relative to the ground. Because the satellite orbits at the same speed that the Earth is turning, the satellite seems to stay in place over a single longitude, though it may drift north to south. When a satellite reaches exactly 42,164 kilometers from the center of the Earth (about 36,000 kilometers from Earth’s surface), it enters a sort of “sweet spot” in which its orbit matches Earth’s rotation.
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