we cannot measure the brightness directly. The light reaching the earth is studied and measured. It is again not measured by energy measuring instrument. The magnitude of the light reaching the earth is measured by a scale proably called apparent magnitude.
also known as "stellate magnitude" (Times 898 - 49 across)
because a star's atmosphere absorbs colors of instead of emitting them, the spectrum of a star is called an absorption spectrum. an absorption spectrum is produced when light from a hot solid or dense gas passes through a less dense, cooler gas. The cooler gas absorbs certain portions of the spectrum.therefore, the black lines of a star's spectrum represent portions of the spectrum that are absorbed by the atmosphere.
Astronomers measure how bright stars are by: First, determining the flux from the star (the rate at which energy reaches us from the star per unit area). This can be done using a CCD camera quite easily. Then, as one knows the distance to the star, one can determine how luminous the star should be to give the required flux.
The amount of starlight received on Earth varies depending on factors like the distance from the star, the star's luminosity, and atmospheric conditions. On average, about 1 billionth of the total light emitted by the Sun reaches Earth's surface, providing energy for life and driving Earth's climate system.
No. A light year measures such large distances that it would be highly impractical to measure anything on Earth. The light year is used to measure distance in space beyond the solar system.
A light meter is commonly used to measure the amount of light under a tree. It measures the intensity of light in lux or foot-candles, giving a numerical value that indicates the level of illumination in that area.
light years
One light year is the distance light travels in one Earth year. So, 70,000 light years would be equivalent to 70,000 Earth years.
Parallax
Parallax
B:See related question;
The amount of starlight received on Earth varies depending on factors like the distance from the star, the star's luminosity, and atmospheric conditions. On average, about 1 billionth of the total light emitted by the Sun reaches Earth's surface, providing energy for life and driving Earth's climate system.
David smallman waz ere 2k12!
How: Earth receives the Sun's radiation as sunlight (and a smaller amount of invisible light, such as infrared and ultraviolet radiation). This is a huge amount of power received by Earth.
light beams are received from the sun.
A "light year" is a measure of distance, derived from "how far light can travel in one Earth year". Thus, if you shine a torch for the amount of time it takes the Earth to orbit the sun exactly once, that light would have travelled the distance of a "light year".
No part of the Earth receives the same amount of light every day, but every point on Earth receives the same amount of light in a whole year.
Beam spreading is when the sun's rays (or angles) spread out because the earth is in it's revolution and rotation. However this is the definition of beam spreading relating light and the amount of light received to earth, not relevant to another meaning. So basically beam spreading is when the sun's light spreads on earth.
Parallax
When the amount of light reflected increases, it is referred to as brightness or luminance. This is a measure of how intense the light appears to the human eye.