While most people don't realize the number of satellites that orbit our Earth, others have already been shocked by illustrations of Earth with a veritable ring of these man-made devices thickly surrounding the planet. So, what exactly are satellites, how many orbit Earth, and how can we see them? Read on to discover the answers to these questions and more!
Though it also refers to bodies that orbit planets or stars, such as moons or planets, the increasingly more usual definition of satellites are, machines launched into space that revolve around the Earth or another body in the solar system. Some say that the "Space Age" truly began in 1957 when the first satellite was launched.
Sputnik 1 orbited Earth for a ground-breaking three months before falling to a fiery death in Earth's atmosphere. Right now, there are over 1,000 working satellites orbiting Earth. This might seem like a big number, but that's because satellites are incredibly useful. Their bird's eye view allows them to collect data quicker and more extensively than ground-based instruments. Satellites have also revolutionized our ability to watch TV - since television signals can only travel in straight lines, they'd often get stopped by mountains or trail off into space, unable to follow the curve of the Earth. Satellites receive TV and phone signals and can send them instantly to different locations on Earth's surface.
Satellites aren't just small; they also include some of the largest and most significant objects in Earth's orbit, like the famed Hubble Telescope and the pioneering International Space Station. These two prime examples, along with about half of the satellites currently in orbit, follow a Low Earth Orbit, meaning that they are close to our planet. Those in Medium Earth Orbit are global positioning system satellites, used to power our handy GPS devices, which have become a big part of daily life down here on Earth.
The highest satellites are those in what is called geosynchronous orbit; meaning that, to the observer on Earth, the satellites don't appear to move across the sky. In fact, these geostationary satellites orbit with the Earth, constantly remaining above the same spot. This type of orbit is ideal for applications like weather forecasting or telecommunications.
Setting aside the hypothetical observer on Earth, what about the actual observer? It turns out that if you head outside around dusk or dawn and wait around 15 minutes under clear, somewhat dark skies, it shouldn't be hard to see a few satellites pass by overhead. Out of the 1,000 working satellites and a whopping 35,000 smaller pieces of space junk, several hundred are visible to the naked eye observer, including the International Space Station and the Hubble Telescope.
The action lover might have one more question left about satellites: do they ever crash into one another? Actually, yes. The orbits of satellites are calculated in an effort to avoid such collisions, and there are organizations tasked with keeping track of satellites in part to prevent instances like this. However, this doesn't stop the rare collision from occurring. In February 2009, for example, an American and a Russian satellite accidentally collided, though this is thought to be the first (and hopefully the last) time something like this has happened.
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