A star is born

A star is born

The NASA managed in february of last year to take a picture of a star birth [1], it is pretty.

That star is HH-30 or V1213 Tauri, it was a newly form star on the taurus molecular cloud. 146 parsec from us, what is a parsec though ?

It is an astronomical unit used of measuring large objects in space. Historically, astronomers have always taken the angle of a star at different time of year to calculate the distance, with biases.

Nowadays the calculation is simpler, one the 2015 General Assembly of the International Astronomical Union, the parsec unit have been standardised to corresponds to 3.085 677 581 … ×10¹⁶ m [2] equivalent to 3,22 light years.

It is the distance to a star whose parralax angle is 1 arcsecond. An arcsecond is a very small angle, a full circle is 360˚, an arcsecond is 1/3600 of one degree.

Even with the proximity of a parsec to light years (1parsec =3,0857×10¹³ kilomètres 3,22 light years), parsec is preferred by scientists and engineer since it is a direct measurement dependant on the angle of the star. Light years are more intuitive and furthermore used for communication but they are always convertion of a direct measurment and prone to approximations.

Source :

[1] NASA. (2025, February 19). Astronomy Picture of the Day. National Aeronautics and Space Administration.
https://apod.nasa.gov/apod/ap250219.html

[2] International Astronomical Union (IAU). (2015). The IAU Strategic Plan 2010–2020: Astronomy for Development, proposed by the XXIX General Assembly of the International Astronomical Union.
https://www.iau.org/Iau/Publications/List-of-Resolutions