Measures of the Universe

Measures of the Universe

Not only distances, mass, volume, density, temperature can be measured. In the Universe the brightness of the stars, the declination, the wavelength and many other magnitudes are also measured.

Let's see what can be measured in the Universe and how it is measured.

Measures of the Universe, basic concepts

Dough: It is the amount of matter of an object.

Volume: It is the space occupied by an object.

Density: It is calculated by dividing the mass of an object by its volume.

Temperature: The amount of heat of an object. The lowest possible temperature in the Universe is 273 ° C below zero (0 ° Kelvin), which is not having any type of energy.

Units for measuring distances

Measuring the Universe is complicated. The usual units often do not work. The distances, time and forces are enormous and, as is evident, cannot be measured directly.

To measure the distance to nearby stars, the technique of parallax. It is about measuring the angle formed by distant objects, the observed star and the Earth, at the two opposite points of their orbit around the Sun, for example, in January and July.

The diameter of the Earth's orbit is 300 million kilometers. Using trigonometry you can calculate the distance to the star. This technique, however, does not work for distant objects, because the angle is too small and the margin of error is too large.

astronomical (ua)
Average distance between the Earth
and the Sun. It is not used outside the
Solar system.
149,600,000 km
Light-yearDistance traveled by light in
one year. If a star is 10
light years, we see it as it was
10 years ago. It is the most practical.
9.46 billion km
63,235.3 ua
Distance from a body that has
a 2 segment parallax
of Arc. The most "scientific."
30.86 billion km
3.26 light years
206,265 ua
To measure astronomical distances

The brightness of the stars

The brightness (stellar magnitude) is a measurement system in which each magnitude is 2,512 times brighter than the next. A star of magnitude 1 is 100 times brighter than one of magnitude 6. The brightest have negative magnitudes.

There are only 20 stars of magnitude equal to or less than 1. The weakest star that has been observed has a magnitude of 23.


The decline is the measure, in degrees, of the angle of an object in the sky above or below the celestial equator.

Each object describes an apparent "declination circle." The distance, in hours, from the latter to the reference circle (which passes through the poles and the position of the Earth at the beginning of spring) is the ascent of the object.

By combining the ascension, the declination and the distance the position relative to the Earth of an object is determined.


The wavelength is the distance between two crests of light waves, electromagnetic or similar. The shorter the length, the greater the frequency. His study provides a lot of data about space.

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