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  2. Canonical units - Wikipedia

    en.wikipedia.org/wiki/Canonical_units

    In astrodynamics, canonical units are defined in terms of some important object’s orbit that serves as a reference. In this system, a reference mass, for example the Sun’s, is designated as 1 “canonical mass unit” and the mean distance from the orbiting object to the reference object is considered the “canonical distance unit”.

  3. Solar radius - Wikipedia

    en.wikipedia.org/wiki/Solar_radius

    Evolution of the solar luminosity, radius and effective temperature compared to the present-day Sun. After Ribas (2009) [3] The uncrewed SOHO spacecraft was used to measure the radius of the Sun by timing transits of Mercury across the surface during 2003 and 2006. The result was a measured radius of 696,342 ± 65 kilometres (432,687 ± 40 miles).

  4. Rømer's determination of the speed of light - Wikipedia

    en.wikipedia.org/wiki/Rømer's_determination_of...

    By timing the eclipses of Jupiter's moon Io, Rømer estimated that light would take about 22 minutes to travel a distance equal to the diameter of Earth's orbit around the Sun. [1] Using modern orbits, this would imply a speed of light of 226,663 kilometres per second, [2] 24.4% lower than the true value of 299,792 km/s. [3]

  5. Jupiter - Wikipedia

    en.wikipedia.org/wiki/Jupiter

    Based on Jupiter's composition, researchers have made the case for an initial formation outside the molecular nitrogen (N 2) snow line, which is estimated at 20–30 AU (3.0–4.5 billion km; 1.9–2.8 billion mi) from the Sun, and possibly even outside the argon snow line, which may be as far as 40 AU (6.0 billion km; 3.7 billion mi).

  6. Astronomical unit - Wikipedia

    en.wikipedia.org/wiki/Astronomical_unit

    Average distance from the Sun — Venus: 0.72 — Average distance from the Sun — Earth: 1.00 — Average distance of Earth's orbit from the Sun (sunlight travels for 8 minutes and 19 seconds before reaching Earth) — Mars: 1.52 — Average distance from the SunJupiter: 5.2 — Average distance from the Sun — Light-hour: 7.2 ...

  7. Equation of time - Wikipedia

    en.wikipedia.org/wiki/Equation_of_time

    Animation showing equation of time and analemma path over one year.. The United States Naval Observatory states "the Equation of Time is the difference apparent solar time minus mean solar time", i.e. if the sun is ahead of the clock the sign is positive, and if the clock is ahead of the sun the sign is negative.

  8. Astronomical coordinate systems - Wikipedia

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

    Angles in the hours ( h), minutes ( m), and seconds ( s) of time measure must be converted to decimal degrees or radians before calculations are performed. 1 h = 15°; 1 m = 15′; 1 s = 15″ Angles greater than 360° (2 π ) or less than 0° may need to be reduced to the range 0°−360° (0–2 π ) depending upon the particular calculating ...

  9. Light-second - Wikipedia

    en.wikipedia.org/wiki/Light-second

    The average distance between Pluto and the Sun (34.72 AU [5]) is 4.81 light-hours. [6] Humanity's most distant artificial object, Voyager 1, has an interstellar velocity of 3.57 AU per year, [7] or 29.7 light-minutes per year. [8] As of 2023 the probe, launched in 1977, is over 22 light-hours from Earth and the Sun, and is expected to reach a ...