for 1,800 years. As constellations were considered to be composed only of the stars that constituted the figure, it was always possible to use any leftover stars to create and squeeze in a new grouping among the established constellations. Furthermore, exploration by Europeans to other parts of the globe exposed them to stars unknown to them. Two astronomers particularly known for greatly expanding the number of southern constellations were Johann Bayer (1572–1625) and Nicolas Louis de Lacaille (1713–1762). Bayer had listed twelve figures made out of stars that were too far south for Ptolemy to have seen; Lacaille created 14 new groups, mostly for the area surrounding South Celestial Pole. Many of these proposed constellations have been formally accepted, but the rest have historically remained as asterisms. In 1928, the International Astronomical Union (IAU) precisely divided the sky into 88 official constellations following geometric boundaries encompassing all of the stars within them. Any additional new selected groupings of stars or former constellations are often considered as asterisms. However, depending on the particular literature source, any technical distinctions between the terms 'constellation' and 'asterism' often remain somewhat ambiguous. Asterisms consisting of first-magnitude stars Some asterims consist completely of bright first-magnitude stars, which mark out simple geometric shapes. The Summer Triangle of Deneb, Altair, and Vega – α Cygni, α Aquilae, and α Lyrae – is prominent in the northern hemisphere summer skies, as its three stars are all of the 1st magnitude. The stars of the Triangle are in the band of the Milky Way which marks the galactic equator, and are in the direction of the galactic center. The Winter Hexagon includes seven of the twenty-two first-magnitude stars visible in the sky, with Pollux, Capella, Aldebaran, Rigel, Sirius and Procyon (the second and fourth closest star visible without aid), and with the 2nd-magnitude Castor on the periphery, and Betelgeuse off-center. It is also known as the Heavenly 'G'''. It encircles the galactic anticenter, as well as incorporates constellations such as Gemini and Orion. It also includes in the background of Aldebaran the Hyades, the nearest star cluster and one of five first-magnitude deep-sky objects, two of which can be seen just north-east of the Hyades, the Pleiades also in the Taurus constellation and the Alpha Persei Cluster (with Alcyone and Mirfak as the brightest stars). Part of the Winter Hexagon the Winter Triangle is visible in the northern sky's winter