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What things must an astronomer measure to calculate a star's absolute brightness?
Wiki User
∙ 6y ago
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.
Wiki User
∙ 11y ago
Wiki User
∙ 12y agoScientists use telescopes to measure the brightness of stars. But before telescopes were invented, scientists judged the brightness of the stars with their naked eyes. They called the brightest stars they could see the first-magnitude stars, and the dimmest stars, sixth magnitude stars. When telescopes were developed, this system had flaws. They could see more stars with the telescope than with the naked eyes. They could also see the differences in brightness as well.
Wiki User
∙ 10y agoApparent Magnitude and Absolute Magnitude.
Apparent magnitude compares how bright stars APPEAR to be, while absolute magnitude measures the actual brightness. Medium size stars that are pretty close will have a brighter "apparent magnitude" than a really huge star a very long distance away.
The description of "magnitude" was developed a long time ago and so as our knowledge has increased, keeping the same description sounds silly, but that's the way it is.
Bright stars were called "first magnitude", and slightly dimmer stars were called "second magnitude", while still dimmer stars got designations like "third magnitude" and fourth magnitude". A seventh magnitude star is barely visible at all, even with good eyes and in a dark sky.
With the invention of more sensitive instruments, scientists were able to distinguish fractions of magnitudes; so a magnitude 1 star is a little brighter than a magnitude 1.3 star. When we need to describe things even brighter than "first magnitude" stars, we say that a zero is brighter than a 1, and a negative 1 is brighter than a zero. Bigger negative numbers are even brighter. (You can see, I hope, how trying to maintain an archaic system in the modern age can cause zany results!) So the planet Venus, which is much brighter than any star, is sometimes a "magnitude -3", while the planet Jupiter (which is a little dimmer) is "magnitude -2".
"Apparent" magnitudes tell us how bright a star APPEARS to be, at its distance, while "absolute magnitude" tells us how bright the stars would be if they were all measured from the SAME distance. So the Sun, which is RIGHT HERE, has an apparent magnitude of -26, meaning INCREDIBLY bright, but an absolute magnitude of 4.8 or so, meaning that if all the stars were lined up at the same distance, our Sun would only be a 4th or 5th magnitude star.
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What is an non-example of absolute brightness?
Anything that is not the measure of intrinsic brightness of a celestial object.
How do you measure the distance to a cepheid?
Cepheids have a certain relationship between their period, and their absolute luminosity. Thus, their absolute luminosity can be determined. Comparing this with their apparent luminosity allows us to calculate their distance.Cepheids have a certain relationship between their period, and their absolute luminosity. Thus, their absolute luminosity can be determined. Comparing this with their apparent luminosity allows us to calculate their distance.Cepheids have a certain relationship between their period, and their absolute luminosity. Thus, their absolute luminosity can be determined. Comparing this with their apparent luminosity allows us to calculate their distance.Cepheids have a certain relationship between their period, and their absolute luminosity. Thus, their absolute luminosity can be determined. Comparing this with their apparent luminosity allows us to calculate their distance.
Use apparent magnitude in a sentence?
The apparent magnitude of a star is a measure of its brightness.
What are the relationships between apparent magnitude and absolute magnitude?
Apparent magnitude is the brightness of an object as seen from Earth without any atmosphere.Absolute magnitude is the brightness of an object as seen from a predetermined distance, depending on the object.For planets, the distance used is 1 AU (Astronomical Units). Stars and galaxies use 10 parsecs which is about 32.616 light years.The dimmer an object is the higher the positive value. The brighter an object is the higher the negative value.Examples:The Sun has an apparent magnitude of -26.74 but an absolute magnitude of 4.83Sirius has an apparent magnitude of -1.46 but an absolute magnitude of -1.42This means that from Earth, the Sun is a lot brighter, but if the Sun was replaced by Sirius, Sirius would be 25 times more luminous.See related links for more information
What is an astrometer?
An astrometer is a device designed to measure the brightness, relation, or apparent magnitude of stars.
What is an non-example of absolute brightness?
Anything that is not the measure of intrinsic brightness of a celestial object.
Who developed the first system to measure a stars brightness?
It was on a Quantitative scale by the Greek astronomer Hipparchus around 130 BC.
How do you measure the distance to a cepheid?
Cepheids have a certain relationship between their period, and their absolute luminosity. Thus, their absolute luminosity can be determined. Comparing this with their apparent luminosity allows us to calculate their distance.Cepheids have a certain relationship between their period, and their absolute luminosity. Thus, their absolute luminosity can be determined. Comparing this with their apparent luminosity allows us to calculate their distance.Cepheids have a certain relationship between their period, and their absolute luminosity. Thus, their absolute luminosity can be determined. Comparing this with their apparent luminosity allows us to calculate their distance.Cepheids have a certain relationship between their period, and their absolute luminosity. Thus, their absolute luminosity can be determined. Comparing this with their apparent luminosity allows us to calculate their distance.
How are absolute magnitude and apparent magnitude alike?
Absolute magnitude and apparent magnitude are the same because they are both ways on how to measure the brightness of a star. Absolute magnitude is how bright is the star if we will see it in a 32.616 light-years distance while apparent magnitude is the brightness of it that we see on Earth.
What is the measure of the star's brightness?
The measure of a star's brightness is its magnitude. A star's brightness as it appears from Earth is called its Apparent Magnitude.Star's brightness is measured by there magnitude.
What the measure of a stars brightness called?
The measure of a star's brightness is its magnitude. A star's brightness as it appears from Earth is called its Apparent Magnitude.Star's brightness is measured by there magnitude.
The measure of a stars brightness is called its what?
Scientists actually use two measurements to identify a star's brightness. One is luminosity, or the energy that star puts out. Another is magnitude, or the amount of light a star puts out.
What measures the brightness of the star?
photographs use to measure the brightness of a star
What is a disadvantage of absolute magnitude?
I assume you mean the absolute magnitude (brightness) of stars. The problem with this is that it can't be directly measured. What astronomers can measure is the apparent magnitude. To make conclusions about the absolute magnitude, they would also have to know the distance to the star, as well as data about extinction, i.e., how much dust and gas there is between us and the start which may make the light look fainter. Note that the absolute magnitude is very important to characterize a star - but it may be difficult to calculate it with much precision.
What is an example absolute brightness?
Anything that is not the measure of intrinsic brightness of a celestial object.
How do you measure the brightness of lamps?
brightness is measured in lumen's in new measurements, or candle power in old. to measure it, you need to get a photometer
What units of measurement do you measure the brightness of stars?
there are two separate ways that astronomers measure the brightness of a start, there is actuall and aparent brightness. In apparent brightness, the measure how bright it looks to all the humans on Earth. However, the actual brightness of a star is different. Say a star is really, really bright, but really far away. That star would look preety dim. Or if a star is not so bright, but really close, like the Sun. The actuall brightness of a star is harder to measure, but is possible by use of waves and stuff like that, I don't know too much about actuall brightness
