Nebulaelae.Docx

Introduction (By: Robert Tarriela and Jemina Cruz)

Definition: *insert gawa ni robert xD"

Formation:

In essence, a nebula is formed when portions of the interstellar medium undergo gravitational collapse. Mutual gravitational attraction causes matter to clump together, forming regions of greater and greater density. From this, stars may form in the center of the collapsing material, who’s ultraviolet ionizing radiation causes the surrounding gas to become visible at optical wavelengths.

History of Nebula Observation (By: Hannah Elisa Mendiola)

Many nebulous objects were noticed in the night sky by astronomers during Classical Antiquity and the Middle Ages. The first recorded observation took place in 150 CE, when Ptolemy noted the presence of five stars in Almagast that appeared nebulous in his book. He also noted a region of luminosity between the constellations Ursa Major and Leo that was not associated with any observable star.

In his Book of Fixed Stars, written in 964 CE, Persian astronomer Abd al-Rahman al-Sufi made the first observation of an actual nebula. According to al-Sufi’s observations, “a little cloud” was apparent in a portion of the night sky where the Andromeda Galaxy is now known to be located. He also cataloged other nebulous objects, such as the Omicron Velorum and Brocchi’s Cluster.

On July 4th, 1054, the supernova that created the Crab Nebula (SN 1054,) was visible to astronomers on Earth, and recorded observations that were made by both Arabic and Chinese astronomers have been identified. While anecdotal evidence exists that other civilizations viewed the supernova, no records have been uncovered.

By the 17th century, improvements in telescopes led to the first confirmed observations of nebulae. This began in 1610, when French astronomer Nicolas-Claude Fabri de Peiresc made the first recorded observation of the Orion Nebula. In 1618, Swiss astronomer Johann Baptist Cysat also observed the nebula; and by 1659, Christiaan Huygens made the...