Mondo Knows Facts
A parsec comes from a tiny parallax angle
One arcsecond of apparent shift equals 3.26 light years of distance Astronomers measure a nearby star's position twice, six months apart, and note how far it shifts against background objects. That angle, called parallax, shrinks as distance grows. A star with a parallax of one arcsecond sits one parsec away, about 206,000 times the Earth-Sun distance. It sits in Mondo's space collection, one of 200 facts that each trace back to the reference below.
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A parsec is a parallax measurement, not a timeIt is the distance at which Earth's orbit subtends one arcsecondA light-year is a measure of distance rather than timeOne light-year equals roughly 9.46 trillion kilometres travelled by light in a yearProxima Centauri is the closest star to our solar systemThe red dwarf star sits roughly four point two light-years away from EarthLeavitt found a yardstick in Cepheid starsThe slower a Cepheid pulses, the more light it truly gives outType Ia supernovae make reliable cosmic rulersThese explosions peak at a similar brightness, so their distance can be read offNorway's coastline is longer than its land bordersMeasured around every fjord, Norway's mainland shore runs roughly 29,000 kilometres
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Tags: parallax, distance, measurement
A parsec comes from a tiny parallax angle: the short answers
- Where does this come from, and can I check it?
- One arcsecond of apparent shift equals 3.26 light years of distance. The figure is taken from Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
- Is this really a space fact?
- Yes. It sits on the Space shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
- What else can I read about it?
- The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.