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  2. Horizon - Wikipedia

    en.wikipedia.org/wiki/Horizon

    View of the ocean with two ships: one in the foreground and one to the left of it on the horizon. Historically, the distance to the visible horizon has long been vital to survival and successful navigation, especially at sea, because it determined an observer's maximum range of vision and thus of communication, with all the obvious consequences for safety and the transmission of information ...

  3. Orbit of Mars - Wikipedia

    en.wikipedia.org/wiki/Orbit_of_Mars

    Extra-close oppositions of Mars happen every 15 to 17 years, when we pass between Mars and the Sun around the time of its perihelion (closest point to the Sun in orbit). The minimum distance between Earth and Mars has been declining over the years, and in 2003 the minimum distance was 55.76 million km, nearer than any such encounter in almost ...

  4. Astronomy on Mars - Wikipedia

    en.wikipedia.org/wiki/Astronomy_on_Mars

    Mars Global Surveyor imaged the Earth and Moon on May 8, 2003, 13:00 UTC, very close to maximum angular elongation from the Sun and at a distance of 0.930 AU from Mars. The apparent magnitudes were given as −2.5 and +0.9. [8]

  5. Celestial navigation - Wikipedia

    en.wikipedia.org/wiki/Celestial_navigation

    Celestial navigation by taking sights of the Sun and the horizon whilst on the surface of the Earth is commonly used, providing various methods of determining position, one of which is the popular and simple method called "noon sight navigation"—being a single observation of the exact altitude of the Sun and the exact time of that altitude ...

  6. Sunset - Wikipedia

    en.wikipedia.org/wiki/Sunset

    Sunset on Mars. On Mars, the setting Sun appears about two-thirds the size it does from Earth, [21] due to the greater distance between Mars and the Sun. The colors are typically hues of blue, but some Martian sunsets last significantly longer and appear far redder than is typical on Earth. [22]

  7. Meridian altitude - Wikipedia

    en.wikipedia.org/wiki/Meridian_altitude

    By subtracting this figure from 90°, he would find that the zenith distance of the Sun is 0°, which is the same as his latitude. If Observer B is standing at one of the geographical poles (latitude 90°N or 90°S ), he would see the Sun on the horizon at an altitude of 0°.

  8. Transit of Earth from Mars - Wikipedia

    en.wikipedia.org/wiki/Transit_of_Earth_from_Mars

    Earth and Moon transiting the Sun in 2084, as seen from Mars. Image created using SpaceEngine Earth and Moon from Mars, as photographed by the Mars Global Surveyor. A transit of Earth across the Sun as seen from Mars takes place when the planet Earth passes directly between the Sun and Mars, obscuring a small part of the Sun's disc for an observer on Mars.

  9. Meridian (astronomy) - Wikipedia

    en.wikipedia.org/wiki/Meridian_(astronomy)

    In another approach known as the horizontal coordinate system, the meridian is divided into the local meridian, the semicircle that contains the observer's zenith and the north and south points of their horizon, [1] [2] and the opposite semicircle, which contains the nadir and the north and south points of their horizon.