Estúdio Horácio Novais, Praça do Rossio, Lisboa, sem data Colecções daFundação Calouste Gulbenkian, Lisboa, Portugal (Flickr Commons)
2017-02-17
Astronomy picture of the day - 2017 February 17 - Polar Ring Galaxy NGC 660
Image Credit & Copyright: CHART32 Team, Processing - Johannes Schedler
Explanation: NGC 660 is featured in this cosmic snapshot. Over 40 million light-years away and swimming within the boundaries of the constellation Pisces, NGC 660's peculiar appearance marks it as a polar ring galaxy. A rare galaxy type, polar ring galaxies have a substantial population of stars, gas, and dust orbiting in rings strongly tilted from the plane of the galactic disk. The bizarre-looking configuration could have been caused by the chance capture of material from a passing galaxy by a disk galaxy, with the captured debris eventually strung out in a rotating ring. The violent gravitational interaction would account for the myriad pinkish star forming regions scattered along NGC 660's ring. The polar ring component can also be used to explore the shape of the galaxy's otherwise unseen dark matter halo by calculating the dark matter's gravitational influence on the rotation of the ring and disk. Broader than the disk, NGC 660's ring spans over 50,000 light-years.
2017-02-16
Astronomy picture of the day - 2017 February 16 - The Tulip and Cygnus X-1
Image Credit & Copyright: Ivan Eder
Explanation: Framing a bright emission region, this telescopic view looks out along the plane of our Milky Way Galaxy toward the nebula rich constellation Cygnus the Swan. Popularly called the Tulip Nebula, the reddish glowing cloud of interstellar gas and dust is also found in the 1959 catalog by astronomer Stewart Sharpless as Sh2-101. About 8,000 light-years distant and 70 light-years across the complex and beautiful nebula blossoms at the center of this composite image. Ultraviolet radiation from young energetic stars at the edge of the Cygnus OB3 association, including O star HDE 227018, ionizes the atoms and powers the emission from the Tulip Nebula. HDE 227018 is the bright star near the center of the nebula. Also framed in the field of view is microquasar Cygnus X-1, one of the strongest X-ray sources in planet Earth's sky. Driven by powerful jets from a black hole accretion disk, its fainter visible curved shock front lies above and right, just beyond the cosmic Tulip's petals
2017-02-15
Fotografias subaquaticas - Polvo
Prémio Fotógrafo Subaquático do ano 2017 - "A maneira como ele se move é tão diferente de qualquer predador em terra, que isto poderia ser na verdade um alienígena de outro mundo", comentou o júri
GABRIEL BARATHIEU/UPY 2017
Astronomy picture of the day - 2017 February 15 - The Calabash Nebula from Hubble
Image Credit: NASA, ESA, Hubble, MAST; Acknowledgement: Judy Schmidt
Explanation: Fast expanding gas clouds mark the end for a central star in the Calabash Nebula. The once-normal star has run out of nuclear fuel, causing the central regions to contract into a white dwarf. Some of the liberated energy causes the outer envelope of the star to expand. In this case, the result is a photogenic proto-planetary nebula. As the million-kilometer per hour gas rams into the surrounding interstellar gas, a supersonic shock front forms whereionized hydrogen and nitrogen glow blue. Thick gas and dust hide the dying central star. The Calabash Nebula, also known as the Rotten Egg Nebula and OH231.8+4.2, will likely develop into a full bipolar planetary nebula over the next 1000 years. The nebula, featured here, is about 1.4 light-years in extent and located about 5000 light-years away toward the constellation of Puppis.
2017-02-14
Fotografia - Lisboa Nocturna - Praça do Rossio
Estúdio Horácio Novais, Praça do Rossio, Lisboa, sem data Colecções da Fundação Calouste Gulbenkian, Lisboa, Portugal (Flickr Commons)
Expressões populares portuguesas - Coisas do Arco-da-Velha
Significado: Coisas inacreditáveis, absurdas, espantosas, inverosímeis.
Origem: A expressão tem origem no Antigo Testamento; arco-da-velha é o arco-íris, ou arco-celeste, e foi
sinal do pacto que Deus fez com Noé: "Estando o arco nas nuvens, Eu ao vê-lo recordar-Me-ei da aliança
eterna concluída entre Deus e todos os seres vivos de toda a espécie que há na terra." (Génesis 9:16)
Arco-da-velha é uma simplificação de Arco da Lei Velha, uma referência à Lei Divina.
Há também diversas histórias populares que defendem outra origem da expressão, como a da existência de
uma velha no arco-íris, sendo a curvatura do arco a curvatura das costas provocada pela velhice, ou devido a
uma das propriedades mágicas do arco-íris - beber a água num lugar e enviá-la para outro, pelo que velha
poderá ter vindo do italiano bere (beber).
Astronomy picture of the day - 2017 February 14 - The Rosette Nebula
Image Credit & Copyright: Evangelos Souglakos
Explanation: Would the Rosette Nebula by any other name look as sweet? The bland New General Catalog designation of NGC 2237 doesn't appear to diminish the appearance of this flowery emission nebula. Inside the nebula lies an open cluster of bright young stars designated NGC 2244. These stars formed about four million years ago from the nebular material and their stellar winds are clearing a hole in the nebula's center, insulated by a layer of dust and hot gas. Ultraviolet light from the hot cluster stars causes the surrounding nebula to glow. The Rosette Nebula spans about 100 light-years across, lies about 5000 light-years away, and can be seen with a small telescope towards theconstellation of the Unicorn (Monoceros).
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