Final answer:
A parsec is equivalent to 3.26 light-years, and it's a unit of distance used by astronomers to measure the vast distances in space, especially using the parallax method.
Step-by-step explanation:
The student asked which unit of distance a parsec is equal to 3.26 times. The correct answer is b) Light-years. So, one parsec is equivalent to 3.26 light-years. This unit of measurement is important in astronomy for describing enormous cosmic distances between celestial objects. Parsecs are particularly useful when using the method of stellar parallax, which involves measuring the apparent shift of a star's position against the background of more distant stars as viewed from two different positions in Earth's orbit around the Sun.
A parsec is defined as the distance at which one astronomical unit subtends an angle of one arcsecond. It turns out that this distance is 206,265 astronomical units (AU), or 3.26 light-years. Conversely, one light-year is about 0.31 parsecs. The parsec is also a key component in the cosmic distance ladder, allowing astronomers to measure distances to nearby stars with precision, as missions like Hipparcos and Gaia provide accurate parallaxes.