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"First magnitude" usually means the brightest 21 stars, as seen from Earth.
Another definition is stars with apparent magnitudes 0.5 to 1.5.
This definition excludes the very brightest stars, like Sirius.
They are the first stars that become visible after sunset and they all have names. Examples are Altair, Aldebaran, Capella, Spica, Antares, Fomalhaut, Deneb, Regulus,
Sirius, etc.
There can be confusion because First Magnitude stars are not stars with an "apparent magnitude" of exactly "one". They are just the brightest stars, but naturally their magnitudes are close to one.
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What is the 4th magnitude star?
First magnitude stars are by definition the brightest stars.Therefore a number of bright stars are:Our SunSiriusCanopusArcturusAlpha Centauri AVegaRigelProcyonAchernarBetelgeuse
What things must an astronomer measure to calculate a star's absolute brightness?
Telescopes, combined with spectroscopy are used for the colors. The apparent brightness can be measured using a telescope with a special "CCD camera". To measure the "real" brightness ("absolute magnitude") you also need to be able to work out the distance to the star.
Why is absolute magnitude of some stars greater than their apparent magnitude for stars?
The apparent magnitude is what we see, and this can be measured directly. The absolute magnitude must be calculated, mainly on the basis of (1) the apparent magnitude, and (2) the star's distance. So, to calculate the absolute magnitude, you must first know the star's distance.
What is the actual amount of light a star gives off?
It is actually absolute magnitude, opposed to apparent magnitude which is how much light stars appear to give off.
The brightness of stars as they appear from Earth is measured by magnitude?
Stars are measured in brilliance called magnitude. The faintest stars visible to the naked eye are mag.6. Brighter ones are mag. 1 or 2, the even brighter stars have negative magnitude. So its like a number line in math: Brighter Fainter -6_-5_-4_-3_-2_-1__0__1_2_3_4_5_6
What are two ways to describe a stars brightness?
Apparent magnitude and absolute magnitude.
What is the 4th magnitude star?
First magnitude stars are by definition the brightest stars.Therefore a number of bright stars are:Our SunSiriusCanopusArcturusAlpha Centauri AVegaRigelProcyonAchernarBetelgeuse
A measure of a stars brightness is called its?
Magnitude. First magnitude descibes many bright stars, and a span of five magnitudes represents a difference of a hundred times in the star's brightness. The dimmest stars seen by a perfect human eye in perfect conditions is 6th magnitude.
What is a stars brightness known as?
A star's brightness is known as its magnitude. Stars with lower magnitude numbers are brighter than stars with a higher magnitude number.
Are the brightest stars low or high magnitude?
The brightest stars have lower magnitude numbers. So a "First magnitude star" is one of the brightest stars there are. Some things are even brighter; the planet Venus is sometimes the third brightest thing in the sky (after the Sun and the Moon). The magnitude of Venus can be as bright as -1. Higher numbers are for dimmer stars. About the dimmest star you could see would be a seventh-magnitude star, but only if the sky were VERY dark.
What the relationship between magnitude and size of the star?
The brightness of a star depends on its temperature, size and distance from the earth. The measure of a star's brightness is called its magnitude. Bright stars are first magnitude stars. Second magnitude stars are dimmer. The larger the magnitude number, the dimmer is the star.The magnitude of stars may be apparent or absolute.
Why is the absolute magnitude of some stars greatar than their apparent magnitude?
The question is: Why is the apparent magnitude of some stars less than their absolute magnitude. Or: Why do some stars not look as bright as they really are ? The answer is: Because they're so far away from us.
What things must an astronomer measure to calculate a star's absolute brightness?
Telescopes, combined with spectroscopy are used for the colors. The apparent brightness can be measured using a telescope with a special "CCD camera". To measure the "real" brightness ("absolute magnitude") you also need to be able to work out the distance to the star.
Which one tells us how bright the stars would appear if all stars were at the same distance ferom the earth?
There are two terms used to describe a stars brightness, absolute magnitude and apparent magnitude. The one you want is absolute magnitude - this is where the stars distance from us is taken out of the equation, effectively comparing the stars brightness side by side from a set distance (10 parsecs or 32.6 light years). Apparent magnitude is the other measure, this is how bright a star apparently looks from Earth. The huge distances and range of distances involved means that you can have very bright stars (high absolute magnitude) that apparently look as bright as a much closer but dimmer (low absolute magnitude) star - their apparent magnitudes might be similar, but they may have vastly different absolute magnitudes.
What are the eight conspicuous stars magnitude 1?
The question is, I think about "apparent magnitude". The question is hard to answer precisely, because there aren't eight stars of magnitude 1 exactly. There is the expression "stars of the first magnitude" which is the 21 brightest stars (in apparent magnitude). Our Sun is not included. Anyway, here is that list starting with Sirius, the brightest (magnitude -1.46) down to Regulus (magnitude +1.36) : Sirius Canopus Arcturus Alpha Centauri Vega Capella Rigel Procyon Betelgeuse Achernar Hadar Altair Acrux (Alpha Crucis) Aldebaren Spica Antares Formalhaut Pollux Deneb Becrux (Beta Crucis) Regulus.
What is meant by the magnitude of stars?
how bright they are.
What is the measure of a stars brightness?
Magnitude.
