Editing Antares (section)

== Observation ==
Antares is visible all night around May 31 of each year, when the star is at [[opposition (astronomy and astrology)|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 (astronomy and astrology)|conjunction]] with the Sun.<ref name="LASCO"/> 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. <!--this period of invisibility is longer in the [[Northern Hemisphere]] than in the [[Southern Hemisphere]], since the star's [[celestial latitude]] is south of the ecliptic.-->

=== History ===
[[File:Antares near the Sun every year around 2 December.jpg|thumb|left|upright|Antares near the Sun on 30 November 2012]]
[[Radial velocity]] variations were observed in the spectrum of Antares in the early 20th century,<ref name=wright/> and attempts were made to derive [[spectroscopic binary|spectroscopic]] orbits.<ref name=lunt/> 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%.<ref name=spencerjones/>

Antares was first reported to have a companion star by [[Johann Tobias Bürg]] during an occultation on April 13, 1819,<ref name="burnham" /> although this was not widely accepted and dismissed as a possible atmospheric effect.<ref name="Johnson1879" /> It was then observed by Scottish astronomer [[James William Grant (astronomer)|James William Grant]] [[Fellow of the Royal Society of Edinburgh|FRSE]] while in [[India]] on 23 July 1844.<ref name=wikisource/> It was rediscovered by [[Ormsby M. Mitchel]] in 1846<ref name=crossley/> and measured by [[William Rutter Dawes]] in April 1847.<ref name=innes/><ref name=dawes/>

In 1952, Antares was reported to vary in brightness. A photographic magnitude range from 3.00 to 3.16 was described.<ref name=cousins/> The brightness has been monitored by the [[American Association of Variable Star Observers]] since 1945,<ref name=aavso/> 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 {{val|1,650|640}} days.<ref name="kiss" /> No separate long secondary period has been detected,<ref name="percy" /> although it has been suggested that primary periods longer than a thousand days are analogous to long secondary periods.<ref name="kiss" />

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').<ref name=hamacher/>

=== Occultations and conjunctions ===
[[File:Antares-R.webm|thumb|right|Lunar Occultation of Antares (reappearance) was observed on 2006 May 14 from The Blue Mountains, 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 star]]s within 6° of the ecliptic (the others are [[Spica]], [[Regulus]] and [[Aldebaran]]), so it can be [[Occultation|occulted]] by the [[Moon]]. The occultation of 31 July 2009 was visible in much of southern Asia and the Middle East.<ref name="iota" /><ref name="timesofindia" /> Every year around December 2 the Sun passes 5° north of Antares.<ref name="LASCO" /> Lunar occultations of Antares are fairly common, depending on the 18.6-year cycle of the [[lunar node]]s. The last cycle ended in 2010 and the next begins in 2023. 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.<ref name=jbaa/> 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.<ref name=nightwatch/> 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.<ref name=chart/>

=== Illumination of Rho Ophiuchi cloud complex ===
Antares is the brightest and most evolved stellar member of the [[Scorpius–Centaurus association]], the nearest [[Stellar association#OB associations|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 {{convert|170|pc|ly|lk=on}} from Earth at the rim of the Upper Scorpius subgroup, and is illuminating the [[Rho Ophiuchi cloud complex]] in its foreground.<ref name=melnik2020/> The [[reflection nebula|illuminated cloud]] is sometimes referred to as the Antares Nebula or is otherwise identified as VdB 107.<ref name="Mamajek 2008 pp. 10–14"/>