His catalogue was extended to about 6,000 stars by Louise Freeland Jenkins in 1952, and to over 8,000 stars by William van Altena in 1995.

In 1924, American astronomer Frank Schlesinger published a catalogue with the parallaxes of almost 2,000 stars, probing stellar distances out to a few dozen light-years from Earth. Over the following decades, astronomers, aided by the improvements in telescope technology gradually grew the catalogs of stellar distances using the parallax method. By the early 20th century, the list of stars with measured parallaxes grew to a few hundred, mostly thanks to the work of Dutch astronomer Jacobus Kapteyn. In the late 1830s, Bessel’s contemporaries and rivals Wilhelm Struve and Thomas Henderson provided one parallax measurement each, bringing the total number to three. This was the beginning of the long and tedious process of building a three-dimensional map of the universe. Based on his observations, Bessel calculated that the star 61 Cygni, one of the stars in the Cygnus constellation, must be about 10 light-years away from Earth.

The first person to succeed at measuring the distance to a star using the parallax method was German astronomer Friedrich Bessel in 1838. Cassini subsequently used those measurements to compute the parallax determining Mars' distance from Earth. In 1672, Italian astronomer Giovanni Cassini and his colleague Jean Richer made simultaneous observations of Mars, with Cassini in Paris and Richer in French Guiana. The ancient Greek astronomer Hipparchus reportedly used observations of a solar eclipse from two different locations to calculate the distance of Earth's celestial companion. The first known astronomical measurement using parallax didn't involve a star but the moon. Hope that this could help someone else to understand a little bit better this argument.The history of parallax measurements in astronomy We will not use this measure (image on the top) but instead we will wait the right time when the star is right in front of the sun so that we can build up a right angle triangle and calculate the distance using tri.

Now we end up with two angle: the first measure α and the second measure β.Īlso there is always one time during the orbit where the star is right in front of our star, so we will use that measure (that we verify with the second 6 months apart) to create the right angle triangle. So we need the next measure 6 month apart to identify a single point where the star is. My wrong assumption was that we know if the star is right in front of the sun, but we can't know that. So we don't know where the star could be. So with a single measure we'll end up with something like this: The reason we need two measurement is because you can't get a point from a single line. The calculation of the angle, as said here is a pure angle measure. After few days of studying and asking I find my answer in this reddit thread

Parallax angle equation