Sirius is gradually moving closer to the Solar System and it is expected to increase in brightness slightly over the next 60,000 years to reach a peak magnitude of −1.68.

This is due to axial precession and proper motion of Sirius itself which moves slowly in the SSW direction, so it will be visible from the southern hemisphere only.

The initially more massive of these, Sirius B, consumed its hydrogen fuel and became a red giant before shedding its outer layers and collapsing into its current state as a white dwarf around 120 million years ago.

Its displacement from the ecliptic causes its heliacal rising to be remarkably regular compared to other stars, with a period of almost exactly 365.25 days holding it constant relative to the solar year.

[32] The inhabitants of the island of Ceos in the Aegean Sea would offer sacrifices to Sirius and Zeus to bring cooling breezes and would await the reappearance of the star in summer.

[36] In 1717, Edmond Halley discovered the proper motion of the hitherto presumed fixed stars[37] after comparing contemporary astrometric measurements with those from the second century AD given in Ptolemy's Almagest.

[11] In a letter dated 10 August 1844, the German astronomer Friedrich Wilhelm Bessel deduced from changes in the proper motion of Sirius that it had an unseen companion.

[52] In 1915, Walter Sydney Adams, using a 60-inch (1.5 m) reflector at Mount Wilson Observatory, observed the spectrum of Sirius B and determined that it was a faint whitish star.

[56] Around the year 150 AD,[57] Claudius Ptolemy of Alexandria, an ethnic Greek Egyptian astronomer of the Roman period, mapped the stars in Books VII and VIII of his Almagest, in which he used Sirius as the location for the globe's central meridian.

[58] He described Sirius as reddish, along with five other stars, Betelgeuse, Antares, Aldebaran, Arcturus, and Pollux, all of which are at present observed to be of orange or red hue.

[57] The discrepancy was first noted by amateur astronomer Thomas Barker, squire of Lyndon Hall in Rutland, who prepared a paper and spoke at a meeting of the Royal Society in London in 1760.

In 1985, German astronomers Wolfhard Schlosser and Werner Bergmann published an account of an 8th-century Lombardic manuscript, which contains De cursu stellarum ratio by St. Gregory of Tours.

[68][69] Nevertheless, historical accounts referring to Sirius as red are sufficiently extensive to lead researchers to seek possible physical explanations.

[63] Similarly, the presence of a third star sufficiently luminous to affect the visible colour of the system in recent millennia is inconsistent with observational evidence.

Scintillations caused by atmospheric turbulence result in rapid, transient changes in the apparent colour of the star, especially when observed near the horizon, although with no particular preference for red.

[71] However, systematic reddening of the star's light results from absorption and scattering by particles in the atmosphere, exactly analogous to the redness of the Sun at sunrise and sunset.

[63] There may be cultural reasons to explain why some ancient observers might have reported the colour of Sirius preferentially when it was situated low in the sky (and therefore apparently red).

In several Mediterranean cultures, the local visibility of Sirius at heliacal rising and setting (whether it appeared bright and clear or dimmed) was thought to have astrological significance and was thus subject to systematic observation and intense interest.

[73] Sirius is visible from almost everywhere on Earth, except latitudes north of 73° N, and it does not rise very high when viewed from some northern cities (reaching only 13° above the horizon from Saint Petersburg).

At the closest approach, it is an observational challenge to distinguish the white dwarf from its more luminous companion, requiring a telescope with at least 300 mm (12 in) aperture and excellent seeing conditions.

[82] The Voyager 2 spacecraft, launched in 1977 to study the four giant planets in the Solar System, is expected to pass within 4.3 light-years (1.3 pc) of Sirius in approximately 296,000 years.

[92] Stellar models suggest that the star formed during the collapsing of a molecular cloud and that, after 10 million years, its internal energy generation was derived entirely from nuclear reactions.

[94] Sirius A is classed as a type Am star, because the spectrum shows deep metallic absorption lines,[95] indicating an enhancement of its surface layers in elements heavier than helium, such as iron.

[102][12] In 1909, Ejnar Hertzsprung was the first to suggest that Sirius was a member of the Ursa Major Moving Group, based on his observations of the system's movements across the sky.

Because of the concept of the yazatas, powers which are "worthy of worship", Tishtrya is a divinity of rain and fertility and an antagonist of apaosha, the demon of drought.

Many nations among the indigenous peoples of North America also associated Sirius with canines; the Seri and Tohono Oʼodham of the southwest note the star as a dog that follows mountain sheep, while the Blackfoot called it "Dog-face".

The ancient Chinese visualized a large bow and arrow across the southern sky, formed by the constellations of Puppis and Canis Major.

The Dogon people are an ethnic group in Mali, West Africa, reported by some researchers to have traditional astronomical knowledge about Sirius that would normally be considered impossible without the use of telescopes.

"[141] According to Noah Brosch cultural transfer of relatively modern astronomical information could have taken place in 1893, when a French expedition arrived in Central West Africa to observe the total eclipse on 16 April.

[157] Throughout the 1990s, several members of the occult group the Order of the Solar Temple committed mass murder-suicide with the goal of leaving their bodies and spiritually "transiting" to Sirius.