February – Febbraio 26 – Astronomy Bulletin Of the Day

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Thousands and thousands of brilliant stars make up this globular cluster, Messier 53, captured with crystal clarity in this image from the NASA/ESA Hubble Space Telescope. Bound tightly by gravity, the cluster is roughly spherical and becomes denser towards its heart. These enormous sparkling spheres are by no means rare, and over 150 exist in the Milky Way alone, including Messier 53. It lies on the outer edges of the galaxy, where many other globular clusters are found, almost equally distant from both the centre of our galaxy and the Sun. Although they are relatively common, the famous astronomer William Herschel, not at all known for his poetic nature, once described a globular cluster as “one of the most beautiful objects I remember to have seen in the heavens”, and it is clear to see why. Globular clusters are much older and larger than open clusters, meaning they are generally expected to contain more old red stars and fewer massive blue stars. But Messier 53 has surprised astronomers with its unusual number of a type of star called blue stragglers. These youngsters are rebelling against the theory of stellar evolution. All the stars in a globular cluster are expected to form around the same time, so they are expected follow a specific trend set by the age of the cluster and based on their mass. But blue stragglers don’t follow that rule; they appear to be brighter and more youthful than they have any right to be. Although their precise nature remains mysterious these unusual objects are probably formed by close encounters, possibly collisions, between stars in the crowded centres of globular clusters. This picture was put together from visible and infrared exposures taken with the Wide Field Channel of Hubble’s Advanced Camera for Surveys.The field of view is approximately 3.4 arcminutes across.

In 1777 Charles Messier discovered M53 in Coma Berenice, a globular cluster 65,000 light-years away.

Nel 1777 Charles Messier scopre M53 nella Chioma di Berenice, un ammasso globulare distante 65.000 anni luce.

François Arago was born in 1786, a French mathematician, physicist, astronomer and politician known for the discovery of the chromatic polarization of light (1811) and, together with A. Fresnel, studied rotary polarization (1817) and the interference of polarized light (1819). His name was given in his honor: to the Arago crater on Mars, to a crater on the Moon (see photo) and to a ring of Neptune.

Nel 1786 nasce François Arago, un matematico, fisico, astronomo e uomo politico francese noto per la scoperta della polarizzazione cromatica della luce (1811) e, insieme con A. Fresnel, studiò la polarizzazione rotatoria (1817) e l’interferenza della luce polarizzata (1819). In suo onore è stato dato il suo nome: al cratere Arago su Marte, ad un cratere sulla Luna (vedi foto) e ad un anello di Nettuno.

Camille Flammarion was born in 1842, an astronomer known above all as a great popularizer whose most famous works are: La pluralité des mondes habités (1862); Les mondes imaginaires et les mondes réels (1865); Astronomie populaire (1867); Histoire du ciel (1872); Les terres du ciel (1877); The Mars planet and its conditions of habitability

Nel 1842 nasce Camille Flammarion, astronomo noto soprattutto come grande divulgatore di cui le opere più famose: La pluralité des mondes habités (1862); Les mondes imaginaires et les mondes réels (1865); Astronomie populaire (1867); Histoire du ciel (1872); Les terres du ciel (1877); La planète Mars et ses conditions d’habitabilité

In 1878 the Italian astronomer Angelo Secchi died, an Italian Jesuit, astronomer and geodesist, founder of astronomical spectroscopy.

Nel 1878 muore l’astronomo italiano Angelo Secchi, gesuita, astronomo e geodeta italiano, fondatore della spettroscopia astronomica.

In 1966, launch from Cape Canaveral of the Saturn IB carrier rocket, an improved version of the first Saturn, with sufficient payload capacity to bring the Apollo Command and Service Module (CSM) or LEM into Earth orbit (the Saturn V was in the of development). In this NASA photo we see the evolutions of the Saturn.

Nel 1966 lancio da Cape Canaveral del razzo vettore Saturn IB, versione migliorata del primo Saturn, con capacità di carico sufficiente a portare nell’orbita terrestre il Modulo di Comando e Servizio (CSM) dell’Apollo o LEM (il Saturn V era in fase di sviluppo). In questa foto NASA vediamo le evoluzioni del Saturn.

Text source: Wikipedia, Nasa

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