In Ptolemy's earth-centered model for the
solar system, Venus's phase is never full as viewed from earth because it
always lies between earth and the sun. In reality, as Galileo first recognized,
Venus is full.
<span>Venus is closer to the Sun than Earth. That
is why we cannot see the full Venus. However, Venus is full (whenever it is on the opposite side
of the Sun from Earth). From Earth, Venus's phases range only between new and
crescent.</span>
A measure of the amount of light given off by a star is its absolute luminosity or magnitude. Absolute magnitude<span> is the measure of </span>intrinsic brightness<span> of a celestial object. It is the hypothetical </span>apparent magnitude<span> of an object at a standard </span>distance<span> of exactly 10 </span>parsecs<span> (32.6 </span>light years<span>) from the </span>observer<span>, assuming no </span>astronomical extinction<span> of starlight. </span>
Include or not include trace gases?
The Trump administration plans to immediately turn back all asylum seekers and who attempts to cross the southwestern border between the legal ports of entry. We looked at more than 2,000 ill children across China, where the pandemic began. We compiled some helpful hints about how to keep safe.
