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The time until Betelgeuse explodes depends on the predicted initial conditions and on the estimate of the time already spent as a red supergiant. The total lifetime from the start of the red supergiant phase to core collapse varies from about 300,000 years for a rotating 25 M ☉ star, 550,000 years for a rotating 20 M ☉ star, and up to a ...
Earth's rotation axis moves with respect to the fixed stars (inertial space); the components of this motion are precession and nutation. It also moves with respect to Earth's crust; this is called polar motion. Precession is a rotation of Earth's rotation axis, caused primarily by external torques from the gravity of the Sun, Moon and other bodies.
At the end of 2019, Betelgeuse appeared to dim significantly as seen from Earth.Researchers eventually determined the dimming was the result of material being ejected from Betelgeuse, which cooled ...
Universal time tracks the Earth's rotation in time, which performs one revolution in about 24 hours. The Earth's rotation is uneven, so UT is not linear with respect to atomic time. It is practically proportional to the sidereal time, which is also a direct measure of Earth rotation. The excess revolution time is called length of day (LOD).
The geological time scale (GTS), as defined by international convention, [3] depicts the large spans of time from the beginning of the Earth to the present, and its divisions chronicle some definitive events of Earth history. Earth formed around 4.54 billion years ago, approximately one-third the age of the universe, by accretion from the solar ...
Called a "mini-moon" of sorts by some, it temporarily entered Earth's orbit on Sept. 29 from the Arjuna asteroid belt, which follows a similar orbital path around the sun as the Earth.
The origin at the centre of Earth means the coordinates are geocentric, that is, as seen from the centre of Earth as if it were transparent. [3] The fundamental plane and the primary direction mean that the coordinate system, while aligned with Earth's equator and pole , does not rotate with the Earth, but remains relatively fixed against the ...
Earth's rotation period relative to the Sun—its mean solar day—is 86,400 seconds of mean solar time (86,400.0025 SI seconds). [157] Because Earth's solar day is now slightly longer than it was during the 19th century due to tidal deceleration , each day varies between 0 and 2 ms longer than the mean solar day.