⚙️ how
How do astronomers measure the distance to a star?
Quick Answer
For nearby stars, they use parallax — the tiny shift in a star’s position as Earth orbits the Sun. The closer the star, the larger the shift.
The Full Story
Parallax is the most direct way to measure stellar distance. Astronomers observe a star from opposite sides of Earth’s orbit, six months apart, and compare its position against distant background stars. The angle is tiny, so the method works best for nearby stars. The European Space Agency’s Gaia mission has measured parallax for more than a billion stars, making it the most detailed 3D map of the Milky Way ever made.
Key Facts
1.Parallax uses Earth’s 1 AU orbit as a baseline
2.Gaia has measured over a billion stars
3.The method is most accurate for stars within our galaxy
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