When Eta Carinae was first catalogued in 1677 by Edmond Halley, it was of the 4th magnitude, but by 1730, observers noticed it had brightened considerably and was, at that point, one of the brightest stars in Carina. In the middle of the 18th century, Nicolas Louis de Lacaille mapped and gave the stars of Argo Navis Bayer designations. He assigned the then second-magnitude star the Greek letter Eta.[9]
Subsequently Eta Carinae dimmed, and by 1782 it appeared to have reverted to its former magnitude. In 1820, it was observed to be growing in brightness again. By 1827, it had brightened more than tenfold and reached its greatest apparent brightness in April 1843. With a magnitude of −0.8, it was the second brightest star in the night-time sky (after Sirius at 8.6 light years away), despite its enormous distance. (To put the relationship in perspective, the relative brightness would be like comparing a candle (representing Sirius) at 14.5 meters (48 feet) to another light source (Eta Carinae) about 10 kilometers (6.2 mi) away, which would appear almost as bright as the candle.)