== == A solar day is the length of time between two successive passes of the sun across the same spot in the sky (e.g. crossing the meridian, overhead). That time period is, on average, 24:00:00, hours, or one mean solar day.
A sidereal day is the length of time between two successive passes of the fixed stars across the sky. That time period is 23:56:04, or one sidereal day.
The difference occurs because, over the course of a year, the earth does one revolution, or "lap" around the sun, so that there must be one less solar day (365.25) per year than there are sidereal days (366.25). Spread over the year, comes to a difference of about four minutes each day.
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The nuclear reactions going on in the heart of the Sun.
The Earth "day" of exactly 24 hours is the "mean solar day""Mean" is basically a scientific way of saying "average". It's called a "solar day " because it's based on the position of the Sun in the sky.There are natural variations in the length of the solar day because of the Earth's elliptical orbit and axial tilt.The "mean solar day" averages out the variations that happen during the year.This makes things much more convenient for everyday life."Mean solar time" is based on the "mean solar day".The "apparent solar day" is the what we actually observe, and its length varies from day to day.A sundial measures "apparent solar time". We can convert this time to mean solar time by using something called "the equation of time".Actually, the sundial shows "local apparent solar time".That's because the time shown by a sundial depends on its exact longitude.For convenience, mean solar time has time zones (based on longitude).So, longitude also affects the relationship between these twomeasures of time.
India astronomers recognized that the earth was a sphere.
Solar. It's rather grandiose to refer to it as an "eclipse". Venus is so far away that it will just be a speck crossing the Sun, and it will reduce the Sun's light by only an almost immeasurable fraction. It's likely that most people will not even be aware of it. Astronomers generally call it a "transit".
By its movement. That means that more than one observation is required - for example, comparison of photographs made on different days.
astronomers.
Mainly astronomers. But cosmologists and astrophysicists will also be interested in outer space.
Astronomers.
no
Astronomers
astronomers
Many astronomers, historians, regular people, and scientisis know about the planets in our Solar system.
People thought the earth was in the center of the solar system
Yes it does. Saturn, like the inner planets and Jovian planets, rotates. Astronomers discovered the Planet Saturn has a full solar day of 10 hours and 47 minutes.
astronomers
the atmosphere
In order to conveniently compare the distances from the various planets, astronomers devised a measure called the "astronomical unit". The Earth is one AU from the Sun. In order to conveniently compare the sizes of other stars to our Sun, astronomers use a "solar mass" as the mass of the Sun. and a "solar radius" as the radius of our Sun. This helps to make the comparisons more obvious to non-astronomers.