Standard candle cosmology

What did standard candles prove?
Standard candles are important in astronomy.
They allow us to measure distance.
If you have two stars of the same type, but one is further away than the other, it looks fainter.
Knowing that they should be the same brightness allows us to work out the distances between them..
What is a standard candle and why is it useful in the context of astronomy?
One of the fundamental tools astronomers use to measure distances are what we call standard candles.
These are the objects for which we have figured out how to determine their absolute brightness by measuring their other parameters.
A basic example would be the Cepheids periodically variable stars..
What is a standard candle in astronomy a level?
A standard candle is an astronomical object that has a known absolute magnitude (intrinsic brightness).
They are extremely important to astronomers since by measuring the apparent magnitude of the object the distance to the source can be determined by using the inverse square law..
What is the formula for the standard candle?
Compute the luminosity of the nearer standard candle: L = 4 pi d² b.
Assume that the farther standard candle has the same luminosity L as the nearer standard candle.
Compute the distance to the farther standard candle: d² = L / (4 pi b).
One of the fundamental tools astronomers use to measure distances are what we call standard candles.
These are the objects for which we have figured out how to determine their absolute brightness by measuring their other parameters.
A basic example would be the Cepheids periodically variable stars.
The most distant, currently known standard candles are a class of star explosions called Type-IA supernovae, where the time it takes light to diminish after the explosion is related to the actual brightness of the explosion itself.
To illustrate the standard candle property of gamma-ray pulsars (and also to thereby confirm the recent first-principle calculation of pulsar gamma-ray emission), we “measure”, via the lightcurve fitting, three distances and one moment of inertia of some weak pulsars.

Standard candles are astronomical objects that make up the rungs of the so-called cosmic distance ladder, a tool for measuring the distances to farther and farther galaxies. The ladder's first rung consists of pulsating stars called Cepheid variables, or Cepheids for short.

A standard ruler is an astronomical object for which the actual physical size is known.
By measuring its angular size in the sky, one can use simple trigonometry to determine its distance from Earth.
In simple terms, this is because objects of a fixed size appear smaller the further away they are.

Standard candle cosmology

What did standard candles prove?

What is a standard candle and why is it useful in the context of astronomy?

What is a standard candle in astronomy a level?

What is the formula for the standard candle?