Measuring the universe

When we measure the univers, we don't only measure distances, mass, volume, density, temperature can be measured. The Universe also measures the brightness of the stars, the decline, the wavelength and many other magnitudes. Measuring the Universe is complicated. Often the usual units do not serve. Distances, time and forces are enormous and clearly cannot be measured directly. The parallax technique is used to measure the distance to the nearby stars.

It is a question of measuring the angle of the distant objects, the star that is observed and the Earth, at the two opposite points of its 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, is not suitable for distant objects, because the angle is too small and the margin of error is very large.

The brightness of the stars
Brightness (star magnitude) is a measuring system in which each magnitude is 2,512 times brighter than the next. A star of magnitude 1 is 100 times brighter than a star 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.


Declination
Declination is the measure, in degrees, of the angle of an object from the sky above or below the celestial equator. Each object describes an apparent "decline circle". The distance, in hours, from this to the circle of reference (which passes through the poles and the position of the Earth at the beginning of spring) is the ascension of the object. Combining ascension, decline and distance determines the relative position of an object to the Earth.