Astronomia e Ciências Espaciais 2015

[Orion]

Daqui a 1h e 45m emissão Slooh que acompanhará o cometa Lovejoy.

 

[Teles]

A Lua hoje:

 

[Orion]

Esta semana Júpiter está em oposição. Melhor altura para ver/fotografar.

 

[Orion]

 

[Orion]

 

[Teles]

Foto de Júpiter tirada esta noite:

 

[camrov8]

http://www.space.com/17933-nasa-television-webcasts-live-space-tv.html lançamento falcon 9

 

[camrov8]

já não vai a lado nenhum hoje, parece que um radar de longo alcance da força areia pifou

 

[Paelagius]

Foto de Júpiter tirada esta noite:

Boa noite,

Partilho convosco uma fotografia registada por um amigo meu por volta da uma e meia da manhã de sábado (07/02). Distância focal 1260mm.

 

[Orion]

Scientists have been counting sunspots since 1610 with small telescopes. Thus it has been verified that the Sun's activity increases every eleven years, according to the interval in the growth of the number of darker and colder spots in comparison with the rest of its surface. The more spots that appear, the more luminous the surrounding areas are, and our star shines brighter.

Nonetheless, the eleven-year cycles do not always have the same intensity. The more intense peaks of the Sun's luminosity were produced in the 20th century, which experts have called the 'modern maximum'. However, an international team of scientists has reviewed the historical data and has verified that there were also elevated values in other periods. "It has been a huge surprise to observe that in the 18th century the levels of the Sun's activity were practically the same as they are now," points out José M. Vaquero, researcher at the University of Extremadura (Spain) and co-author of the research, a review of the number of sunspots recorded in the last 400 years.

The results, published in the journal 'Space Science Reviews', also reveals that in other periods the opposite occurred, such as the Maunder minimum (1645-1715), when the sunspots practically disappeared and solar activity was drastically reduced.

"A proper estimate of the past and present activity of the Sun, our main source of light and heat, is crucial in understanding numerous phenomena that occur on Earth, especially to rule out the role of the Sun in global warming," says Vaquero, "but we come up against the problem that two indices or ways of calculating historical solar activity exist, and their data does not coincide when describing what happened before the 20th century."

SD

 

[Orion]

 

[StormRic]

O teu trabalho de selecção, recolha de informação, de vídeos, etc é sempre notável! Muito obrigado!

Espectaculares estes, especialmente o do Sol!

 

[Orion]

 

[Orion]

Uma estrela alienígena passou pelo nosso sistema solar... há 70 mil anos. Segundo uma internacional equipa de astrónomos, a estrela esteve cinco vezes mais perto do que a nossa vizinha mais próxima, do sistema triplo Alpha Centauri.

A anã vermelha, conhecida como estrela de Scholz, andou pelos limites do sistema solar, na nuvem de Oort, tendo por companheira uma anã castanha, ou seja, uma estrela falhada.

DN

A notícia está mal escrita. Numa primeira instância é uma estrela. Depois é uma binária. Ainda assim, não deve ter sido agradável:

When Scholz’s star buzzed the solar system, it probably slipped inside the Oort cloud, a shell of trillions of comets that envelops the solar system. While such close encounters can hurl a barrage of comets toward the sun, Scholz’s star’s flyby apparently spared the inner solar system.

SN

Os meteoritos, em vez de chocarem com a Terra, como por exemplo na Rússia, deviam eram ser encaminhados para a Lua. Ao menos o pessoal via algo extraordinário e inofensivo.

Ainda em relação ao par supramencionado:

Scholz's star currently lies 20 light years away - making it a fairly nearby system. But it showed very slow tangential motion for a star this close. This indicated that it was either moving away from us or towards a future close encounter with the Solar System.

Scholz's star came relatively close, but the binary system (the red dwarf and its brown dwarf companion) has a low mass and it was speeding by. These factors conspired to make its effect on the Oort Cloud very small.

While this is the closest flyby detected so far, Dr Mamajek thinks it's not uncommon for alien stars to buzz the Sun. He says a star probably passes through the Oort Cloud every 100,000 years, or so.

But he suggests an approach as close - or closer - than that made by Scholz's star is somewhat rarer. Dr Mamajek said mathematical simulations show such an event occurs on average about once every nine million years.

BBC

 

[Orion]