The Universe is a place too big to measure its size on a trip weekend, luckily there are the standard candles.
Standard candles are phenomena very violent and with very regular properties, which are used by astronomers to measure distances in the Universe without having to travel with a giant meter in their backpack. The term is a bad translation from English, level: Ana Botella.
The original term is Standard Candles or standard candles and refers to the fact that these phenomena have some very well defined characteristics that allow us to know its distance from Earth just by looking at its light. We see in more detail what these standard candles are and how their can measure their distance.
What are the most common standard candles?
The standard candles are not a closed group of celestial objects but are worth any astronomical phenomena that have very well defined characteristics and standardized. For example a star is useless Because stars can be very diverse in size and can range in color from redder to bluish tones than blue supergiants.
One of the phenomena most used as a standard candle are supernovae, for many reasons. The first reason is that they are very bright phenomena, so much so that they sometimes shine brighter than the galaxy to which they belong. Besides that supernovae have a very characteristic light emission they just depend on what kind of supernova it is.
This makes supernovae some of the best standard candles possible Since we know perfectly well what light they emit and when we receive this light, transformed by what is between us and the supernova, we can determine things like how long have you traveled if there were dust clouds on the way
Understanding the light of a standard candle and the distance at which it is located
We have already told you some time how to know what gases a planet contains, or how to know the speed of a star just by looking at its light; and here all this is reused in almost the same way. So much the Doppler effect as the spectrum of light that we receive from the standard candle are vital to understand the universe in which we live.
For example, if we see that the spectrum that we expect to receive from the supernova is bitten at certain wavelengths, we will know that in the middle there is a gas cloud that absorbs at that frequencyLooking at the tables we will know what gas it is and in what quantity. If on the other hand we see that all the light is displaced towards a redder color, we know that light has traveled extensively or passed near large objects.
All of these measurements are possible because the standard candles have always the same light pattern And we know perfectly well that any discrepancy is solely the result of what has happened in the journey between the standard candle and us.
Bonus: With this standard candle method the accelerated expansion of the Universe was discovered, which was Nobel Prize in 2011