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Consequently, a magnitude 1 star is about 2.5 times brighter than a magnitude 2 star, about 2.5 2 times brighter than a magnitude 3 star, about 2.5 3 times brighter than a magnitude 4 star, and so on. This is the modern magnitude system, which measures the brightness, not the apparent size, of stars.
Stars in binary systems (or other multiples) are listed by their total or combined brightness if they appear as a single star to the naked eye, or listed separately if they do not. As with all magnitude systems in astronomy , the scale is logarithmic and inverted i.e. lower/more negative numbers are brighter.
about 400,000 times as bright as mean full Moon −25.60: star Sun: seen from Mars at aphelion: −25.00: Minimum brightness that causes the typical eye slight pain to look at: −23.00: star Sun: seen from Jupiter at aphelion −21.70: star Sun: seen from Saturn at aphelion −21.00: star Sun: seen from Earth on an overcast midday measuring ...
c. 300 BC — star catalog of Timocharis of Alexandria; c. 134 BC — Hipparchus makes a detailed star map; c. 150 — Ptolemy completes his Almagest, which contains a catalog of stars, observations of planetary motions, and treatises on geometry and cosmology; c. 705 — Dunhuang Star Chart, a manuscript star chart from the Mogao Caves at Dunhuang
The Bortle dark-sky scale (usually referred to as simply the Bortle scale) is a nine-level numeric scale that measures the night sky's brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution .
The final characteristic provided in the tables and star charts is the star's brightness, expressed in terms of apparent magnitude. Magnitude is a logarithmic scale of brightness, designed so that a body of one magnitude is approximately 2.512 times brighter than a body of the next magnitude.
The star, whose mass is roughly half that of the Sun, is currently 62 light-years from the Solar System. It was first noticed in 1999 using data from the Hipparcos satellite, and was estimated to pass less than 1.3 light-years (0.40 pc) from the Sun in 1.4 million years. [ 73 ]
An online star chart; Monthly sky maps for every location on Earth Archived 2007-09-13 at the Wayback Machine; The Evening Sky Map – Free monthly star charts and calendar for northern hemisphere, southern hemisphere, and equatorial sky watchers. Sky Map Online – Free interactive star chart (showing over 1.2 million stars up to magnitude 12)