for Antares, showing
AAVSO visual and
V band data, along with
Hipparcos data. Adapted from Marici and Guinan (2025) Antares is visible all night around May 31 of each year, when the star is at
opposition to the
Sun. Antares then rises at dusk and sets at dawn as seen at the equator. For two to three weeks on either side of November 30, Antares is not visible in the night sky from mid-northern latitudes, because it is near
conjunction with the Sun. In higher northern latitudes, Antares is only visible low in the south in summertime. Higher than 64° northern latitude, the star does not rise at all. Antares is easier to see from the southern hemisphere due to its southerly declination. In the whole of
Antarctica, the star is circumpolar as the whole continent is above 64° S latitude.
History Radial velocity variations were observed in the spectrum of Antares in the early 20th century, and attempts were made to derive
spectroscopic orbits. It became apparent that the small variations could not be due to orbital motion, and they were actually caused by pulsation of the star's atmosphere. Even in 1928, it was calculated that the size of the star must vary by about 20%. Antares was first reported to have a companion star by
Johann Tobias Bürg during an occultation on April 13, 1819, although this was not widely accepted and dismissed as a possible atmospheric effect. It was then observed by Scottish astronomer
James William Grant FRSE while in
India on 23 July 1844. It was rediscovered by
Ormsby M. Mitchel in 1846 and measured by
William Rutter Dawes in April 1847. In 1952, Antares was reported to vary in brightness. A photographic magnitude range from 3.00 to 3.16 was described. The brightness has been monitored by the
American Association of Variable Star Observers since 1945, and it has been classified as an
LC slow irregular variable star, whose
apparent magnitude slowly varies between extremes of +0.6 and +1.6, although usually near magnitude +1.0. There is no obvious periodicity, but statistical analyses have suggested periods of 1,733 days or days. No separate long secondary period has been detected, although it has been suggested that primary periods longer than a thousand days are analogous to long secondary periods. Research published in 2018 demonstrated that
Ngarrindjeri Aboriginal people from
South Australia observed the variability of Antares and incorporated it into their oral traditions as Waiyungari (meaning 'red man').
Occultations and conjunctions , Australia. Antares B reappears first, followed by Antares A 7.53 seconds later. Antares is 4.57 degrees south of the
ecliptic, one of four
first magnitude stars within 6° of the ecliptic (the others are
Spica,
Regulus and
Aldebaran), so it can be
occulted by the
Moon. The occultation of 31 July 2009 was visible in much of southern Asia and the Middle East. Every year around December 2 the Sun passes 5° north of Antares. Lunar occultations of Antares are fairly common, depending on the 18.6-year cycle of the
lunar nodes. The current cycle began in 2023 and the last cycle ended in 2010. Shown at right is a video of a reappearance event, clearly showing events for both components. Antares can also be occulted by the planets, e.g.
Venus, but these events are rare. The last occultation of Antares by Venus took place on September 17, 525 BC; the next one will be November 17, 2400. Other planets have been calculated not to have occulted Antares over the last millennium, nor will they in the next millennium, as most planets stay near the ecliptic and pass north of Antares. Venus will be extremely near Antares on October 19, 2117, and every eight years thereafter through to October 29, 2157, it will pass
south of the star.
Illumination of Rho Ophiuchi cloud complex Antares is the brightest and most evolved stellar member of the
Scorpius–Centaurus association, the nearest
OB association to the Sun. It is a member of the Upper Scorpius subgroup of the association, which contains thousands of stars with a mean age of 11 million years. Antares is located about from Earth at the rim of the Upper Scorpius subgroup, and is illuminating the
Rho Ophiuchi cloud complex in its foreground. The
illuminated cloud is sometimes referred to as the Antares Nebula or is otherwise identified as VdB 107. ==Stellar system==