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  2. Heliosphere - Wikipedia

    en.wikipedia.org/wiki/Heliosphere

    For comparison, the Earth orbits the Sun at about 30 km/s, the ISS orbits the Earth at about 7.7 km/s, airliners fly over the ground at about 0.2–0.3 km/s, a car on a typical limited-access highway achieves about 0.03 km/s, and humans walk around 0.001 km/s.) The interstellar medium, although very low in density, nonetheless has a relatively ...

  3. Heliocentric orbit - Wikipedia

    en.wikipedia.org/wiki/Heliocentric_orbit

    Heliocentric orbit. A heliocentric orbit (also called circumsolar orbit) is an orbit around the barycenter of the Solar System, which is usually located within or very near the surface of the Sun. All planets, comets, and asteroids in the Solar System, and the Sun itself are in such orbits, as are many artificial probes and pieces of debris.

  4. Kepler's laws of planetary motion - Wikipedia

    en.wikipedia.org/wiki/Kepler's_laws_of_planetary...

    Planet orbiting the Sun in a circular orbit (e=0.0) Planet orbiting the Sun in an orbit with e=0.5 Planet orbiting the Sun in an orbit with e=0.2 Planet orbiting the Sun in an orbit with e=0.8 The red ray rotates at a constant angular velocity and with the same orbital time period as the planet, =. S: Sun at the primary focus, C: Centre of ...

  5. Analemma - Wikipedia

    en.wikipedia.org/wiki/Analemma

    In astronomy, an analemma (/ ˌænəˈlɛmə /; from Ancient Greek ἀνάλημμα (analēmma) 'support') [a] is a diagram showing the position of the Sun in the sky as seen from a fixed location on Earth at the same mean solar time, as that position varies over the course of a year. The diagram resembles a figure eight.

  6. Ecliptic - Wikipedia

    en.wikipedia.org/wiki/Ecliptic

    The ecliptic is the apparent path of the Sun throughout the course of a year. [4] Because Earth takes one year to orbit the Sun, the apparent position of the Sun takes one year to make a complete circuit of the ecliptic. With slightly more than 365 days in one year, the Sun moves a little less than 1° eastward [5] every day.

  7. Earth - Wikipedia

    en.wikipedia.org/wiki/Earth

    Earth is rounded into an ellipsoid with a circumference of about 40,000 km. It is the densest planet in the Solar System. Of the four rocky planets, it is the largest and most massive. Earth is about eight light-minutes away from the Sun and orbits it, taking a year (about 365.25 days) to complete one revolution.

  8. Orbital eccentricity - Wikipedia

    en.wikipedia.org/wiki/Orbital_eccentricity

    e. In astrodynamics, the orbital eccentricity of an astronomical object is a dimensionless parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit (or capture orbit), and greater than ...

  9. Astronomical coordinate systems - Wikipedia

    en.wikipedia.org/wiki/Astronomical_coordinate...

    The fundamental plane is the plane of the Earth's orbit, called the ecliptic plane. There are two principal variants of the ecliptic coordinate system: geocentric ecliptic coordinates centered on the Earth and heliocentric ecliptic coordinates centered on the center of mass of the Solar System.