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Parallax Formula:
Where:
- \( d \) is distance in parsecs
- \( p \) is parallax angle in arcseconds
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Parallax is the apparent shift in position of a nearby star against the background of distant objects when viewed from different positions in Earth's orbit. It's a fundamental method for measuring distances to stars.
The calculator uses the parallax formula:
Where:
Explanation: A star with a parallax of 1 arcsecond is at a distance of 1 parsec (about 3.26 light-years).
Details: Parallax measurements provide the most direct method for determining distances to nearby stars and form the foundation of the cosmic distance ladder.
Tips: Enter the parallax angle in arcseconds (must be greater than 0). For example, Proxima Centauri has a parallax of 0.7687 arcseconds.
Q1: What is the practical limit of parallax measurements?
A: Current space telescopes like Gaia can measure parallax angles as small as 0.01 milliarcseconds, reaching stars up to about 10,000 parsecs away.
Q2: Why is parallax measured in arcseconds?
A: Arcseconds (1/3600 of a degree) are used because stellar parallax angles are extremely small - even the nearest stars show less than 1 arcsecond of parallax.
Q3: How accurate are parallax measurements?
A: Modern space-based measurements are accurate to about 0.01 milliarcseconds for bright stars, though atmospheric effects limit ground-based measurements to about 0.01 arcseconds.
Q4: What is a parsec?
A: A parsec (parallax-second) is the distance at which 1 AU subtends an angle of 1 arcsecond, equal to about 3.26 light-years or 30.9 trillion kilometers.
Q5: Can parallax measure distances to galaxies?
A: No, parallax is only useful for nearby stars within our galaxy. Other methods like standard candles are used for galactic distances.