A Nebulosa Da Lagoa, A Trífida E A NGC 6559, Os Girassóis De Sagittarius. BY NASA APP.

What are Gravitational Waves?

Gravitational waves are ‘ripples’ in the fabric of space-time caused by some of the most violent and energetic processes in the Universe. Albert Einstein predicted the existence of gravitational waves in 1916 in his general theory of relativity.

Einstein’s mathematics showed that massive accelerating objects (such as neutron stars or black holes orbiting each other) would disrupt space-time in such a way that ‘waves’ of distorted space would radiate from the source (like the movement of waves away from a stone thrown into a pond). Furthermore, these ripples would travel at the speed of light through the Universe, carrying with them information about their cataclysmic origins, as well as invaluable clues to the nature of gravity itself.

The strongest gravitational waves are produced by catastrophic events such as colliding black holes, 

the collapse of stellar cores (supernovae), coalescing neutron stars or white dwarf stars, the slightly wobbly rotation of neutron stars that are not perfect spheres, and the remnants of gravitational radiation created by the birth of the Universe itself.

hough gravitational waves were predicted to exist in 1916, actual proof of their existence wouldn’t arrive until 1974, 20 years after Einstein’s death. In that year, two astronomers working at the Arecibo Radio Observatory in Puerto Rico discovered a binary pulsar–two extremely dense and heavy stars in orbit around each other. This was exactly the type of system that, according to general relativity, should radiate gravitational waves. Knowing that this discovery could be used to test Einstein’s audacious prediction, astronomers began measuring how the period of the stars’ orbits changed over time. After eight years of observations, it was determined that the stars were getting closer to each other at precisely the rate predicted by general relativity. This system has now been monitored for over 40 years and the observed changes in the orbit agree so well with general relativity, there is no doubt that it is emitting gravitational waves.

Since then, many astronomers have studied the timing of pulsar radio emissions and found similar effects, further confirming the existence of gravitational waves. But these confirmations had always come indirectly or mathematically and not through actual 'physical’ contact.

That was the case up until September 14, 2015, when LIGO, for the first time, physically sensed  distortions in spacetime itself caused by passing gravitational waves generated by two colliding black holes nearly 1.3 billion light years away! LIGO and its discovery will go down in history as one of the greatest human scientific achievements.

How are gravitational waves detected?

When a gravitational wave passes by Earth, it squeezes and stretches space. LIGO can detect this squeezing and stretching. Each LIGO observatory has two “arms” that are each more than 2 miles (4 kilometers) long. A passing gravitational wave causes the length of the arms to change slightly. The observatory uses lasers, mirrors, and extremely sensitive instruments to detect these tiny changes. Watch the animation below to see how this works!

Lucky for us here on Earth, while the origins of gravitational waves can be extremely violent, by the time the waves reach the Earth they are millions of times smaller and less disruptive. In fact, by the time gravitational waves from the first detection reached LIGO, the amount of space-time wobbling they generated was thousands of times smaller than the nucleus of an atom! Such inconceivably small measurements are what LIGO was designed to make. To find out how LIGO can achieve this task, visit LIGO’s Interferometer. 

Source: LIGO & spaceplace.nasa.gov

Image credit: LIGO/VIRGO (SXS, the Simulating eXtreme Spacetimes) &  NASA/Goddard Space Flight Center

As efemérides estão de volta, para que você que pediu, conto com a sua ajuda para compartilhar esse vídeo e ajudar a divulgar a astronomia pelo mundo.

Essa semana nos céus do Brasil:

11 de Agosto - Júpiter próximo da estrela Regulus, a alfa da constelação do Leão e abaixo de Mercúrio no horizonte oeste, logo depois do pôr-do-Sol.

12 de Agosto - Chuva de Meteoros Delta Aquarídeos, ainda ativa com cerca de 20 meteoros por hora. Radiante alto no céu a partir das 22:00.

13 de Agosto - Pico da Chuva de Meteoros dos Perseidas, taxa de 95 a 100 meteoros por hora, no Brasil a sua visualização é prejudicada, radiante, muito baixo no horizonte por volta das 5 da manhã.

14 de Agosto - Lua Nova

15 de Agosto - Lua com cerca de 1.3% de iluminação entre Júpiter e Mercúrio no horizonte oeste logo após o pôr-do-sol, um grande desafio para a astrofotografia.

16 de Agosto - Lua com cerca de 4.3% de iluminação próxima a Mercúrio logo após o pôr-do-Sol no horizonte oeste.

17 de Agosto - Lua no apogeu, maior distância da Terra, aproximadamente 405849 km.

As informações sobre os locais de pouso da missão Mars 2020, eu retirei de um artigo do site da revista Science:

http://news.sciencemag.org/space/2015/08/mars-scientists-tap-ancient-river-deltas-and-hot-springs-promising-targets-2020-rover

Meus contatos:

BLOG: http://www.spacetoday.com.br

FACEBOOK: http://www.facebook.com/spacetoday

TWITTER: http://twitter.com/spacetoday1

YOUTUBE: http://www.youtube.com/spacetodaytv

Obrigado pela audiência e boa diversão!!!

This new NASA/ESA Hubble Space Telescope image shows the center of the Lagoon Nebula, an object with a deceptively tranquil name, in the constellation of Sagittarius. The region is filled with intense winds from hot stars, churning funnels of gas, and energetic star formation, all embedded within an intricate haze of gas and pitch-dark dust.

Image Credit: NASA/JPL/ESA/J. Trauger 

Neste momento começo a assistir a primeira temporada da série @theexpanse.

O que essa série tem a nos mostrar sobre o possível futuro de colonização de outros planetas?!

The latest results from the “Cheshire Cat” group of galaxies show how manifestations of Einstein’s 100-year-old theory can lead to new discoveries today. Astronomers have given the group this name because of the smiling cat-like appearance. Some of the feline features are actually distant galaxies whose light has been stretched and bent by the large amounts of mass, most of which is in the form of dark matter detectable only through its gravitational effect, found in the system. 

Image credit: NASA / STScI / Chandra & Hubble

What is it Like to Visit Jupiter?

Jupiter is the largest planet in our solar system. For some perspective, if it were hollow, more than 1,300 Earths could fit inside of it! The giant planet contains two-thirds of all the planetary mass in the solar system and holds more than dozens of moons in its gravitational grip. But what about a visit to this giant planet?

Let’s be honest…Jupiter is not a nice place to visit. It’s a giant ball of gas and there’s nowhere to land. Any spacecraft – or person – passing through the colorful clouds gets crushed and melted. On Jupiter, the pressure is so strong it squishes gas into liquid. Its atmosphere can crush a metal spaceship like a paper cup.

Jupiter’s stripes and swirls are cold, windy clouds of ammonia and water. Jupiter’s Great Red Spot is a giant storm BIGGER THAN EARTH! This storm has lasted hundreds of years.

Since Jupiter’s atmosphere is made up of mostly hydrogen and helium, it’s poisonous. There’s also dangerous radiation, more than 1,000 times the lethal level for a human.  

Scientists think that Jupiter’s core may be a thick, super hot soup…up to 50,000 degrees! Woah!

The Moons

Did you know that Jupiter has its own “mini solar system” of 50 moons? Scientists are most interested in the Galilean satellites – which are the four largest moons discovered by Galileo Galilei in 1610. 

Today, Galileo would be astounded to know some of the facts about these moons. The moon Io has active volcanos. Ganymede has its own magnetic field while Europa has a frozen crust with liquid-water underneath making it a tempting place to explore for future missions.

When Juno arrives to Jupiter on July 4, it will bring with it a slew of instruments such as infrared imager/spectrometer and vector magnetometer among the half a dozen other scientific tools in its payload.

Juno will avoid Jupiter’s highest radiation regions by approaching over the north, dropping to an altitude below the planet’s radiation belts – which are analogous to Earth’s Van Allen belts, but far more deadly – and then exiting over the south. To protect sensitive spacecraft electronics, Juno will carry the first radiation shielded electronics vault, a critical feature for enabling sustained exploration in such a heavy radiation environment.

Follow our Juno mission on the web, Facebook, Twitter, YouTube and Tumblr.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com

NGC 6960 (Western Veil nebula) & Horsehead Nebula and the Flame Nebula

by David Wills

Constellations

A constellation is a group of stars that are considered to form imaginary outlines or meaningful patterns on the celestial sphere, typically representing animals, mythological people or gods, mythological creatures, or manufactured devices. The 88 modern constellations are formally defined regions of the sky together covering the entire celestial sphere.

Origins for the earliest constellations likely goes back to prehistory, whose now unknown creators collectively used them to related important stories of either their beliefs, experiences, creation or mythology. As such, different cultures and countries often adopted their own set of constellations outlines, some that persisted into the early 20th Century. Adoption of numerous constellations have significantly changed throughout the centuries. Many have varied in size or shape, while some became popular then dropped into obscurity. Others were traditionally used only by various cultures or single nations.

The Western-traditional constellations are the forty-eight Greek classical patterns, as stated in both Aratus’s work Phenomena or Ptolemy’s Almagest — though their existence probably predates these constellation names by several centuries. Newer constellations in the far southern sky were added much later during the 15th to mid-18th century, when European explorers began travelling to the southern hemisphere. Twelve important constellations are assigned to the zodiac, where the Sun, Moon, and planets all follow the ecliptic. The origins of the zodiac probably date back into prehistory, whose astrological divisions became prominent around 400BCE within Babylonian or Chaldean astronomy.

In 1928, the International Astronomical Union (IAU) ratified and recognized 88 modern constellations, with contiguous boundaries defined by right ascension and declination. Therefore, any given point in a celestial coordinate system lies in one of the modern constellations. Some astronomical naming systems give the constellation where a given celestial object is found along with a designation in order to convey an approximate idea of its location in the sky. e.g. The Flamsteed designation for bright stars consists of a number and the genitive form of the constellation name.

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Detectando Ondas Gravitacionais Com a Missão GAIA - Space Today TV Ep.1057

As ondas gravitacionais, para quem ainda não sabe, tem um espectro, assim como a radiação eletromagnética tem o seu.

Esse espectro é chamado de espectro gravitacional.

Dentro do espectro gravitacional, atualmente, com o LIGO e VIRGO nós só conseguimos detectar ondas gravitacionais provenientes da fusão de buracos negros de massa estelar e da fusão de estrelas de nêutrons.

Essas, digamos, são ondas gravitacionais com frequências mais altas.

Mas lógico que existe a ideia e a vontade de se detectar ondas gravitacionais de frequências baixas.

Essas são produzidas, por exemplo, pela colisão de buracos negros supermassivos.

Nós já avançamos um pouco nesse sentido, já que a tecnologia da LISA, um detector espacial nos moldes do LIGO já foi testada e promete funcionar.

Existe também, como já falei aqui a técnica de usar os pulsares, a chamada Pulsar Timing Array.

Essa técnica é interessante, pois ela usa a observação dos pulsares, e calcula a mudança na frequência aparente dos pulsos com relação à passagem de uma onda gravitacional, gerada pela fusão de buracos negros supermassivos, por exemplo.

com base nessa ideia, um grupo de astrofísicos está propondo algo maravilhoso.

Eles querem usar a missão GAIA, da Agência Espacial Europeia, que mede com precisão a posição de bilhões de estrelas na Via Láctea como um detector de ondas gravitacionais de baixa frequência.

Para isso, a ideia é usar não a variação de pulsos dos pulsares, mas sim a aparente modificação na posição das estrelas observadas pela GAIA, ou seja, suas oscilações para detectar as ondas gravitacionais.

A passagem de uma onda gravitacional, que acaba causando uma oscilação no tecido do espaço-tempo, muda a posição das estrelas, a polarização da onda gravitacional pode ser detectada e assim teríamos a detecção de um tipo novo de onda gravitacional.

A vantagem é que a missão GAIA já está em funcionamento no espaço, já faz essas medidas, ou seja, essa aplicação pode ser testada a qualquer momento.

Os astrônomos realmente viram que o estudo das ondas gravitacionais pode trazer muitos novos conhecimentos sobre o universo, e entender os buracos negros supermassivos é algo que os deixa muito animados.

Vamos aguardar por novidades nessa área.

Enquanto a Lua passava em frente do Sol durante o eclipse total do dia 21 de Agosto de 2017, um fotógrafo da NASA capturou uma foto que pode ser considerada mais rara do que o próprio eclipse.

Joel Kowsky, um dos editores de fotografia da agência, foi até Banner no Wyoming, para ver o eclipse total do Sol, quando ele fotografou a Estação Espacial Internacional passando na frente do Sol crescente.

Abaixo você pode ver um vídeo que foi feito usando uma câmera de alta velocidade que registrou 1500 frames por segundo. Ele também fotografou a ISS com uma câmera padrão.

Essa alta velocidade é necessária pois a ISS tem o tamanho de um campo de futebol, orbita a Terra a cerca de 300 km de altura e se move a uma velocidade 17500 milhas por hora.

Para fazer esse belo registro é necessário um pouco de sorte e meses e meses de planejamento.

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