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This phase lasts about 30 million years, after which, over the course of a further 100,000 years, the Sun's remaining outer layers will fall away, ejecting a vast stream of matter into space and forming a halo known (misleadingly) as a planetary nebula. The ejected material will contain the helium and carbon produced by the Sun's nuclear ...
Thus, the Sun occupies 0.00001% (1 part in 10 7) of the volume of a sphere with a radius the size of Earth's orbit, whereas Earth's volume is roughly 1 millionth (10 −6) that of the Sun. Jupiter, the largest planet, is 5.2 AU from the Sun and has a radius of 71,000 km (0.00047 AU; 44,000 mi), whereas the most distant planet, Neptune, is 30 AU ...
For example, the synodic period of the Moon's orbit as seen from Earth, relative to the Sun, is 29.5 mean solar days, since the Moon's phase and position relative to the Sun and Earth repeats after this period. This is longer than the sidereal period of its orbit around Earth, which is 27.3 mean solar days, owing to the motion of Earth around ...
Birth of the Sun: 17–18 gal 3937 Ma: Oceans appear on Earth 16.889 gal 3800 Ma: Life begins on Earth: 15.555 gal 3500 Ma: Prokaryotes appear 12 gal 2700 Ma: Bacteria appear 10 gal 2250 Ma: Eukaryian period [5] [6] first appearance of eukaryotes [7] Stable continents appear 6.8 gal 1530 Ma: Multicellular organisms appear 2.4 gal 540 Ma ...
Regarding the fixed stars, the Sun appears from Earth to revolve once a year along the ecliptic through the zodiac, and so Greek astronomers categorized it as one of the seven planets (Greek planetes, "wanderer"); the naming of the days of the weeks after the seven planets dates to the Roman era. [228] [229] [230]
On April 4, 2024, four planets will align on the same side of the sun as Earth. According to Star Walk , an astronomy app and developer, Venus, Mars, Saturn and Neptune will be visible.
Spotting the planets will require clear skies since Mercury and Jupiter only get about 6 degrees above the horizon by the time the sun rises around 5:30 am, said Teets.
On a prograde planet like the Earth, the sidereal day is shorter than the solar day. At time 1, the Sun and a certain distant star are both overhead. At time 2, the planet has rotated 360° and the distant star is overhead again (1→2 = one sidereal day). But it is not until a little later, at time 3, that the Sun is overhead again (1→3 = one solar day). More simply, 1→2 is a complete ...