Por Mais De Duas Décadas, Desde A Descoberta Do Primeiros Exoplaneta, Os Astrônomos Já Descobriram

#YearInSpace Reddit AMA

NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko will return from a year-long mission to the International Space Station on Tuesday, March 1. Research conducted during this mission will help prepare us for future voyages beyond low-Earth orbit.

On Friday, March 4 at 11 p.m. EST, we will host a Reddit AMA with scientists and medical doctors from our Johnson Space Center. During the AMA, they will answer your questions about everything from how microgravity affects the human body to how astronauts’ food intake is closely monitored while on-orbit. Ask us anything about the science behind the One Year Mission!

Participants include:

Julie Robinson, Ph.D., NASA’s Chief Scientist for the International Space Station

John Charles, Ph.D., Associate Manager for International Science for NASA’s Human Research Program

Scott M. Smith, Ph.D., Nutritional Biochemistry Laboratory Manager for NASA’s Human Research Program

Dr. Shannan Moynihan, NASA Flight Surgeon

Mark Guilliams, Strength and Conditioning Coach

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

The Moon in Motion

Happy New Year! And happy supermoon! Tonight, the Moon will appear extra big and bright to welcome us into 2018 – about 6% bigger and 14% brighter than the average full Moon. And how do we know that? Well, each fall, our science visualizer Ernie Wright uses data from the Lunar Reconnaissance Orbiter (LRO) to render over a quarter of a million images of the Moon. He combines these images into an interactive visualization, Moon Phase and Libration, which depicts the Moon at every day and hour for the coming year. 

Want to see what the Moon will look like on your birthday this year? Just put in the date, and even the hour (in Universal Time) you were born to see your birthday Moon.

Our Moon is quite dynamic. In addition to Moon phases, our Moon appears to get bigger and smaller throughout the year, and it wobbles! Or at least it looks that way to us on Earth. This wobbling is called libration, from the Latin for ‘balance scale’ (libra). Wright relies on LRO maps of the Moon and NASA orbit calculations to create the most accurate depiction of the 6 ways our Moon moves from our perspective.

1. Phases

The Moon phases we see on Earth are caused by the changing positions of the Earth and Moon relative to the Sun. The Sun always illuminates half of the Moon, but we see changing shapes as the Moon revolves around the Earth. Wright uses a software library called SPICE to calculate the position and orientation of the Moon and Earth at every moment of the year. With his visualization, you can input any day and time of the year and see what the Moon will look like!

2. Shape of the Moon

Check out that crater detail! The Moon is not a smooth sphere. It’s covered in mountains and valleys and thanks to LRO, we know the shape of the Moon better than any other celestial body in the universe. To get the most accurate depiction possible of where the sunlight falls on the lunar surface throughout the month, Wright uses the same graphics software used by Hollywood design studios, including Pixar, and a method called ‘raytracing’ to calculate the intricate patterns of light and shadow on the Moon’s surface, and he checks the accuracy of his renders against photographs of the Moon he takes through his own telescope.

3. Apparent Size 

The Moon Phase and Libration visualization shows you the apparent size of the Moon. The Moon’s orbit is elliptical, instead of circular - so sometimes it is closer to the Earth and sometimes it is farther. You’ve probably heard the term “supermoon.” This describes a full Moon at or near perigee (the point when the Moon is closest to the Earth in its orbit). A supermoon can appear up to 14% bigger and brighter than a full Moon at apogee (the point when the Moon is farthest from the Earth in its orbit). 

Our supermoon tonight is a full Moon very close to perigee, and will appear to be about 14% bigger than the July 27 full Moon, the smallest full Moon of 2018, occurring at apogee. Input those dates into the Moon Phase and Libration visualization to see this difference in apparent size!

4. East-West Libration

Over a month, the Moon appears to nod, twist, and roll. The east-west motion, called ‘libration in longitude’, is another effect of the Moon’s elliptical orbital path. As the Moon travels around the Earth, it goes faster or slower, depending on how close it is to the Earth. When the Moon gets close to the Earth, it speeds up thanks to an additional pull from Earth’s gravity. Then it slows down, when it’s farther from the Earth. While this speed in orbital motion changes, the rotational speed of the Moon stays constant. 

This means that when the Moon moves faster around the Earth, the Moon itself doesn’t rotate quite enough to keep the same exact side facing us and we get to see a little more of the eastern side of the Moon. When the Moon moves more slowly around the Earth, its rotation gets a little ahead, and we see a bit more of its western side.

5. North-South Libration

The Moon also appears to nod, as if it were saying “yes,” a motion called ‘libration in latitude’. This is caused by the 5 degree tilt of the Moon’s orbit around the Earth. Sometimes the Moon is above the Earth’s northern hemisphere and sometimes it’s below the Earth’s southern hemisphere, and this lets us occasionally see slightly more of the northern or southern hemispheres of the Moon! 

6. Axis Angle

Finally, the Moon appears to tilt back and forth like a metronome. The tilt of the Moon’s orbit contributes to this, but it’s mostly because of the 23.5 degree tilt of our own observing platform, the Earth. Imagine standing sideways on a ramp. Look left, and the ramp slopes up. Look right and the ramp slopes down. 

Now look in front of you. The horizon will look higher on the right, lower on the left (try this by tilting your head left). But if you turn around, the horizon appears to tilt the opposite way (tilt your head to the right). The tilted platform of the Earth works the same way as we watch the Moon. Every two weeks we have to look in the opposite direction to see the Moon, and the ground beneath our feet is then tilted the opposite way as well.

So put this all together, and you get this:

Beautiful isn’t it? See if you can notice these phenomena when you observe the Moon. And keep coming back all year to check on the Moon’s changing appearance and help plan your observing sessions.

Follow @NASAMoon on Twitter to keep up with the latest lunar updates. 

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

There’s Going to Be an Outburst!

Watch the Perseid Meteor Shower at Its Peak Tonight

The last time we had an outburst, that is a meteor shower with more meteors than usual, was in 2009. This year’s Perseid meteor shower is predicted to be just as spectacular starting tonight!

Plan to stay up late tonight or set your alarm clock for the wee morning hours to see this cosmic display of “shooting stars” light up the night sky. Known for it’s fast and bright meteors, tonight’s annual Perseid meteor shower is anticipated to be one of the best meteor viewing opportunities this year.

For stargazers experiencing cloudy or light-polluted skies, a live broadcast of the Perseid meteor shower will be available via Ustream overnight tonight and tomorrow, beginning at 10 p.m. EDT.

“Forecasters are predicting a Perseid outburst this year with double normal rates on the night of Aug. 11-12,” said Bill Cooke with NASA’s Meteoroid Environments Office in Huntsville, Alabama. “Under perfect conditions, rates could soar to 200 meteors per hour.”

Every Perseid meteor is a tiny piece of the comet Swift-Tuttle, which orbits the sun every 133 years. When Earth crosses paths with Swift-Tuttle’s debris, specks of comet-stuff hit Earth’s atmosphere and disintegrate in flashes of light. These meteors are called Perseids because they seem to fly out of the constellation Perseus.

Most years, Earth might graze the edge of Swift-Tuttle’s debris stream, where there’s less activity. Occasionally, though, Jupiter’s gravity tugs the huge network of dust trails closer, and Earth plows through closer to the middle, where there’s more material.

This is predicted be one of those years!

Learn more about the Perseids!

Make sure to follow us on Tumblr for your regular dose of space.

Plutão, o pequeno planeta anão, localizado nos confins do nosso Sistema Solar, que até pouco mais de um ano atrás não passava de um amontoado de pixels nas melhores imagens que tínhamos dele, hoje, é um dos objetos mais fascinantes e mais estudado pelo menos por aqueles que estudam ciência planetária.

Além disso, certamente é o objeto que mais surpresas tem nos revelado nesse último ano de intensas pesquisas.

Como já falei aqui para vocês, o próprio Alan Stern, resumiu numa frase toda a agitação nos estudos sobre Plutão, dizendo, simplesmente, que Plutão é o novo Marte.

Essa semana a revista Nature trouxe uma série de 4 artigos sobre Plutão, artigos que mostram estudos feitos principalmente sobre a Sputnik Planitia, sobre o possível oceano na sua subsuperfície, sobre o papel dela na orientação da órbita de Plutão entre outras coisas.

A planície possivelmente se formou com o choque de um objeto do Cinturão de Kuiper com cerca de 250 km de diâmetro a aproximadamente 4 bilhões de ano atrás.

Quando se criou essa enorme bacia, ela foi preenchida com uma água densa, combinada com o nitrogênio da superfície, formando ali um excesso de massa que fez com que Plutão sofresse uma rotação, reorientando-o com relação a Caronte.

Toda vez que se fala em oceano num mundo congelado, a primeira pergunta que vem na cabeça, ou o primeiro pensamento é, será que existe vida nesse oceano? Esse é um pensamento meio que óbvio já que a vida na Terra, como a conhecemos começou nos oceanos.

O sistema de Plutão, ou seja, o planeta anão e seus satélites é um sistema rico em amônia, a amônia já foi detectada em Caronte e nos demais satélites de Plutão, indicando que muito provavelmente existe amônia no interior de Plutão.

A amônia seria o elemento responsável para não deixar que o oceano abaixo da superfície de Plutão congele, ele é mantido numa viscosidade semelhante a de um mel.

As condições não são boas, o oceano tem amônia, é muito frio, tem água salgada, ou seja, não é um lugar para se encontrar germes, peixes, lulas gigantes, mas como pode acontecer em Titã que algum tipo de organismo poderia começar a existir nos oceanos de amônia, poderia ter um novo tipo de vida adaptável a esse ambiente.

De acordo com os pesquisadores, a vida pode suportar quase tudo, as salmoras, o frio extremo, o calor extremo, mas dificilmente suportaria a quantidade de amônia existente ali para manter o oceano no estado líquido.

Todas essas ideias sobre o oceano de Plutão são validas, mas são só inferências, sem medidas diretas, se quisermos realmente provar a existência desse oceano, teríamos que mandar uma sonda para Plutão que entraria em órbita e realizaria medidas de gravidade, provando a presença ou não do oceano.

Uma implicação importante desse trabalho é levantar a questão sobre a possibilidade de se encontrar oceanos em outros objetos do Cinturão de Kuiper, será que a fronteira do Sistema Solar é repleta de oceanos protegidos? E a vida, será que pode proliferar nesses oceanos? Por enquanto só ficamos com as especulações.

(via https://www.youtube.com/watch?v=H_LOJJm29C8)

A fotografia desta semana mostra fitas de gás e poeira em torno do centro da galáxia espiral barrada NGC 1398. Esta galáxia situa-se na constelação da Fornalha, a aproximadamente 65 milhões de anos-luz de distância da Terra.

Em vez de começarem no meio da galáxia e espiralarem para o exterior, os braços em espiral da NGC 1398 têm origem numa barra direita, formada de estrelas, que corta a região central da galáxia. Uma grande parte das galáxias em espiral — cerca de dois terços — apresenta esta estrutura, no entanto ainda não é claro se e como é que estas barras afectam o comportamento e o desenvolvimento das suas galáxias.

Esta imagem foi criada a partir de dados obtidos pelo instrumento FORS2 (FOcal Reducer/low dispersion Spectrograph 2), montado no Very Large Telescope do ESO (VLT) no Observatório do Paranal, no Chile, e mostra a NGC 1398 em grande detalhe, dos escuros trilhos de poeira que sarapintam os braços em espiral às regiões de formação estelar em tons rosa que aparecem nas regiões mais externas.

A imagem foi criada no âmbito do programa Jóias Cósmicas do ESO, o qual visa obter imagens de objetos interessantes, intrigantes ou visualmente atrativos, utilizando os telescópios do ESO, para efeitos de educação e divulgação científica. O programa utiliza tempo de telescópio que não pode ser usado em observações científicas. Todos os dados obtidos podem ter igualmente interesse científico e são por isso postos à disposição dos astrónomos através do arquivo científico do ESO. Crédito da Imagem: ESO

High above Saturn

via reddit

What is Gravitational Lensing?

A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer, that is capable of bending the light from the source as the light travels towards the observer. This effect is known as gravitational lensing, and the amount of bending is one of the predictions of Albert Einstein’s general theory of relativity.

This illustration shows how gravitational lensing works. The gravity of a large galaxy cluster is so strong, it bends, brightens and distorts the light of distant galaxies behind it. The scale has been greatly exaggerated; in reality, the distant galaxy is much further away and much smaller. Credit: NASA, ESA, L. Calcada

There are three classes of gravitational lensing:

1° Strong lensing: where there are easily visible distortions such as the formation of Einstein rings, arcs, and multiple images.

Einstein ring. credit: NASA/ESA&Hubble

2° Weak lensing: where the distortions of background sources are much smaller and can only be detected by analyzing large numbers of sources in a statistical way to find coherent distortions of only a few percent. The lensing shows up statistically as a preferred stretching of the background objects perpendicular to the direction to the centre of the lens. By measuring the shapes and orientations of large numbers of distant galaxies, their orientations can be averaged to measure the shear of the lensing field in any region. This, in turn, can be used to reconstruct the mass distribution in the area: in particular, the background distribution of dark matter can be reconstructed. Since galaxies are intrinsically elliptical and the weak gravitational lensing signal is small, a very large number of galaxies must be used in these surveys.

The effects of foreground galaxy cluster mass on background galaxy shapes. The upper left panel shows (projected onto the plane of the sky) the shapes of cluster members (in yellow) and background galaxies (in white), ignoring the effects of weak lensing. The lower right panel shows this same scenario, but includes the effects of lensing. The middle panel shows a 3-d representation of the positions of cluster and source galaxies, relative to the observer. Note that the background galaxies appear stretched tangentially around the cluster.

3° Microlensing: where no distortion in shape can be seen but the amount of light received from a background object changes in time. The lensing object may be stars in the Milky Way in one typical case, with the background source being stars in a remote galaxy, or, in another case, an even more distant quasar. The effect is small, such that (in the case of strong lensing) even a galaxy with a mass more than 100 billion times that of the Sun will produce multiple images separated by only a few arcseconds. Galaxy clusters can produce separations of several arcminutes. In both cases the galaxies and sources are quite distant, many hundreds of megaparsecs away from our Galaxy.

Gravitational lenses act equally on all kinds of electromagnetic radiation, not just visible light. Weak lensing effects are being studied for the cosmic microwave background as well as galaxy surveys. Strong lenses have been observed in radio and x-ray regimes as well. If a strong lens produces multiple images, there will be a relative time delay between two paths: that is, in one image the lensed object will be observed before the other image.

As an exoplanet passes in front of a more distant star, its gravity causes the trajectory of the starlight to bend, and in some cases results in a brief brightening of the background star as seen by a telescope. The artistic concept illustrates this effect. This phenomenon of gravitational microlensing enables scientists to search for exoplanets that are too distant and dark to detect any other way.Credits: NASA Ames/JPL-Caltech/T. Pyle

Explanation in terms of space–time curvature

Simulated gravitational lensing by black hole by: Earther

In general relativity, light follows the curvature of spacetime, hence when light passes around a massive object, it is bent. This means that the light from an object on the other side will be bent towards an observer’s eye, just like an ordinary lens. In General Relativity the speed of light depends on the gravitational potential (aka the metric) and this bending can be viewed as a consequence of the light traveling along a gradient in light speed. Light rays are the boundary between the future, the spacelike, and the past regions. The gravitational attraction can be viewed as the motion of undisturbed objects in a background curved geometry or alternatively as the response of objects to a force in a flat geometry.

A galaxy perfectly aligned with a supernova (supernova PS1-10afx) acts as a cosmic magnifying glass, making it appear 100 billion times more dazzling than our Sun. Image credit: Anupreeta More/Kavli IPMU.

To learn more, click here. 

Nessa semana, aqui em Parintins, costuma ser bastante movimentado.

Porém, devido a pandemia, quando eu fui comprar pão no final da tarde de ontem. Eu percebi que a cidade estava irreconhecível... Sem visitantes, sem sons de toadas, sem alegorias.

A cidade de Parintins está nos dias de festa religiosa, e então, resolvi relembrar a visita no local mais alto da torre da catedral, onde está localizado a estátua de Nossa Senhora do Carmo. #TorredaCatedraldeParintins Data de registro: 16 de julho de 2018 às 18h18