How scientists determine the distance to distant stars and galaxies

Reading any news related to space, we learn that this or that event took place in a distant galaxy at a distance of many light years.

So in ordinary life, we measure the distance to an object with a ruler or tape measure, to measure traversed route or determining the distance from one point to another, we use GPS trackers or data from satellites. But how do scientists measure distances to distant galaxies? Let's take a look at this issue.

How to measure distance to a distant star

I think it is already clear to everyone that the distance to the closest star to the Sun is measured in hundreds of trillions kilometers, and we simply do not have a "mega-line" to reach the object and measure the distance to it.

So in these dimensions geometry comes to the rescue of scientists. In fact, astronomers learned how to determine the distance to space objects in ancient Greece. And to measure the distance, they used the trigonometric parallax method, which is enclosed in next: first, we measure the angle between the surface of the Earth and the object to which we need to find out distance. Then we move away from the measuring point to the maximum possible distance (the principle works here, the more the better) and repeat the angle measurements.

So, as a result of such a simple manipulation, you and I get an isosceles triangle, whose base is the distance we have traveled.

And it turns out that for a given geometric figure we know the base and angles, which means that through simple calculations we can easily get the distance to the object.

In order to maximize the accuracy of the measurement, astronomers use the diameter of the Earth's orbit as the base. To do this, measure the angle at the same point on the Earth, but with an interval of exactly six months.

But that's not all. After all, there are incredibly distant objects and the above method is not enough to measure them. In this case, the method of standard candles comes to the rescue of scientists.

This method is based on a decrease in the brightness of the glow of stars with an increase in the distance to the observer. For these purposes, scientists use the brightness of some stars as standard candles (after all, their parameters have already been studied quite well).

And now, using simple physical laws, scientists are calculating how far to move away an object from an observer so that its brightness falls to the level that we observe from the surface Earth.

It is in such simple ways that scientists determine the distances to the most distant galaxies that can be detected in the sky using the most modern optical devices.

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