What is orbit?

An orbit is the path an object follows when it moves around another object because of gravity. Imagine tying a ball to a string and swinging it around - the ball’s circular path is like an orbit, only the “string” is the invisible pull of gravity.

Let's break it down

  • Gravity: The force that pulls two objects toward each other. The bigger the object (like Earth), the stronger its pull.
  • Speed: If an object moves fast enough, it keeps missing the surface and keeps circling instead of falling straight down.
  • Balance: An orbit happens when the forward speed of the object exactly balances the pull of gravity. Too slow and it falls; too fast and it escapes into space.
  • Shapes: Most orbits are oval (elliptical), but they can be nearly circular or very stretched out.

Why does it matter?

Orbits let us place satellites, space stations, and probes where they can stay for months or years without using fuel to stay up. They also determine how long a day is on other planets, affect climate, and are essential for GPS navigation, communications, and weather forecasting.

Where is it used?

  • Communication satellites: TV, internet, and phone signals travel through satellites in geostationary or low‑Earth orbits.
  • Navigation: GPS, GLONASS, Galileo, and BeiDou rely on satellites circling Earth.
  • Science: Space telescopes (like Hubble) and Earth‑observation satellites orbit to collect data.
  • Space travel: The International Space Station, Moon missions, and Mars probes all follow orbital paths.
  • Military: Reconnaissance and early‑warning satellites use specific orbits for coverage.

Good things about it

  • Fuel efficiency: Once in orbit, an object needs very little fuel to stay there.
  • Continuous coverage: Satellites can provide constant services (e.g., TV broadcast) over large areas.
  • Predictability: Orbits follow well‑known physics, making their positions easy to calculate.
  • Global reach: A single satellite can serve users worldwide, especially in remote regions.

Not-so-good things

  • Space debris: Defunct satellites and rocket parts create clutter that can damage active spacecraft.
  • Launch cost: Getting a payload into orbit is expensive and requires powerful rockets.
  • Orbital decay: Low‑Earth orbits gradually lose altitude due to atmospheric drag, eventually causing re‑entry.
  • Limited lifespan: Satellites run out of power or suffer wear, needing replacement or upgrades.