# data[].attributes.body
Fobos e Deimos são 2 luas de marte e foram descobertas pelo astrônomo Asaph Hill, do Observatório Naval dos Estados Unidos, em 1877.

# data[].attributes.attachment_link.readable_text
Uma das coisas extraordinárias a respeito das luas de Marte, Fobos e Deimos, é que a existência delas fora prevista nas Viagens de Gulliver. Jonathan Swift quase acertou até mesmo os períodos orbitais. Isso foi em 1726, 15 anos antes das luas de Marte terem sido, de fato, descobertas. É praticamente certo que Swift soubesse de uma previsão do astrônomo alemão Johannes Kepler, que acreditava que as relações geométricas governavam os céus. Como a Terra tinha uma Lua e Júpiter quatro, Kepler argumentava que, certamente, o planeta Marte deveria ter duas.

Fobos e Deimos as duas luas de Marte

Fobos e Deimos foram descobertas pelo astrônomo Asaph Hill, do Observatório Naval dos Estados Unidos, em 1877. Mas ele quase deixou escapar a descoberta. Após noites de insucesso procurando pelas luas, Hall desistiu, desanimado. Entretanto, sua esposa, Angelina Stickney, mandou-o de volta para o telescópio. Ele finalmente descobriu e batizou Fobos (medo) e Deimos (Terror), nomes dos cavalos que puxavam a carruagem de Ares o deus grego da guerra, cujo o nome dado na cultura romana é Marte.

Fobos

Fobos tem um raio de aproximadamente 11 km e possui cerca de 7 vezes a massa de sua irmã Deimos. Outro fato interessante sobre Fobos é que, é a lua mais próxima de seu planeta em todo sistema solar, e devido a esse fato cientistas da NASA afirma que um dia ela irá se chocar com o planeta vermelho.

Separada de Marte por uma distância de menos de 6 mil km (para se ter uma ideia essa distância equivale a sessenta e quatro vezes a distância entre a Lua e a Terra), Fobos se aproxima de Marte dois metros a cada cem anos, baseado nisso astrônomos da NASA acreditam que dentro de cerca de 30 a 50 milhões de anos ela irá se chocar com o planeta vermelho.

Deimos a pequena lua

É a menor e mais externa das pequenas luas marcianas. Enquanto Fobos gira ao redor do planeta mais rápido do que a rotação de Marte, aparecendo duas vezes no céu noturno do planeta, Deimos completa uma volta mais lentamente, levando um pouco mais do que um dia marciano. Tem forma de batata, feita de uma rocha tão negra quanto o carvão. Difere de Fobos no fato da sua superfície ser mais lisa e por suas crateras serem preenchidas com poeira resultante de impactos. Uma das crateras mais proeminentes foi batizada de Swift em homenagem a Jonathan Swift, que especulou em sua obra de ficção a respeito da existência das luas de Marte, muito antes de elas serem descobertas.

# data[].attributes.attachment_link.description
Uma das coisas extraordinárias a respeito das luas de Marte, Fobos e Deimos, é que a existência delas fora prevista nas Viagens de Gulliver. Jonathan Swift quase acertou até mesmo os períodos orbitais. Isso foi em 1726, 15 anos antes das luas de Marte terem sido, de fato, descobertas.

# data[].attributes.attachment_link.title
The world reacts to the death of physicist Stephen Hawking

# data[].attributes.attachment_link.description
Reaction to the death of theoretical physicist Stephen Hawking:

# data[].attributes.body
Em março de 2013, cientistas da missão Planck, da Agência Espacial Europeia, divulgaram este mapa que apresenta o universo a partir da captação da "luz mais antiga" no céu, identificada por radiação cósmica. Ele equivale ao cosmos quando tinha apenas 380 mil anos.

# data[].attributes.headline
Imagem detalhada de Plutão foi capturada pela sonda da missão New Horizons

# data[].attributes.subject
Imagem detalhada de Plutão foi capturada pela sonda da missão New Horizons

# data[].attributes.body
Famosa estrutura geológica de Richat, conhecida também como Olho da África, com diâmetro de cerca de 50 km, localizada na parte mauritana do deserto de Saara (fotografada do espaço).

# data[].attributes.headline
Imagem do Monte Sharp em Marte foi feita pelo Rover Curiosity da NASA

# data[].attributes.subject
Imagem do Monte Sharp em Marte foi feita pelo Rover Curiosity da NASA

# data[].attributes.headline
Os oceanos de Marte formaram-se cedo, possivelmente devido às erupções volcanicas

# data[].attributes.subject
Os oceanos de Marte formaram-se cedo, possivelmente devido às erupções volcanicas

# data[].attributes.attachment_link.readable_text
The early ocean known as Arabia (left, blue) would have looked like this when it formed 4 billion years ago on Mars, while the Deuteronilus ocean, about 3.6 billion years old, had a smaller shoreline. Both coexisted with the massive volcanic province Tharsis, located on the unseen side of the planet, which may have helped support the existence of liquid water. The water is now gone, perhaps frozen underground and partially lost to space, while the ancient seabed is known as the northern plains. Credit: Robert Citron images, UC Berkeley

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million years earlier and were not as deep as once thought.

The proposal by geophysicists at the University of California, Berkeley, links the existence of oceans early in Mars history to the rise of the solar system's largest volcanic system, Tharsis, and highlights the key role played by global warming in allowing liquid water to exist on Mars.

"Volcanoes may be important in creating the conditions for Mars to be wet," said Michael Manga, a UC Berkeley professor of earth and planetary science and senior author of a paper appearing in Nature this week and posted online March 19.

Those claiming that Mars never had oceans of liquid water often point to the fact that estimates of the size of the oceans don't jibe with estimates of how much water could be hidden today as permafrost underground and how much could have escaped into space. These are the main options, given that the polar ice caps don't contain enough water to fill an ocean.

The new model proposes that the oceans formed before or at the same time as Mars' largest volcanic feature, Tharsis, instead of after Tharsis formed 3.7 billion years ago. Because Tharsis was smaller at that time, it did not distort the planet as much as it did later, in particular the plains that cover most of the northern hemisphere and are the presumed ancient seabed. The absence of crustal deformation from Tharsis means the seas would have been shallower, holding about half the water of earlier estimates.

"The assumption was that Tharsis formed quickly and early, rather than gradually, and that the oceans came later," Manga said. "We're saying that the oceans predate and accompany the lava outpourings that made Tharsis."

It's likely, he added, that Tharsis spewed gases into the atmosphere that created a global warming or greenhouse effect that allowed liquid water to exist on the planet, and also that volcanic eruptions created channels that allowed underground water to reach the surface and fill the northern plains.
Following the shorelines
The model also counters another argument against oceans: that the proposed shorelines are very irregular, varying in height by as much as a kilometer, when they should be level, like shorelines on Earth.

This irregularity could be explained if the first ocean, called Arabia, started forming about 4 billion years ago and existed, if intermittently, during as much as the first 20 percent of Tharsis's growth. The growing volcano would have depressed the land and deformed the shoreline over time, which could explain the irregular heights of the Arabia shoreline.

Similarly, the irregular shoreline of a subsequent ocean, called Deuteronilus, could be explained if it formed during the last 17 percent of Tharsis's growth, about 3.6 billion years ago.

"These shorelines could have been emplaced by a large body of liquid water that existed before and during the emplacement of Tharsis, instead of afterwards," said first author Robert Citron, a UC Berkeley graduate student. Citron will present a paper about the new analysis on March 20 at the annual Lunar and Planetary Science conference in Texas.

Tharsis, now a 5,000-kilometer-wide eruptive complex, contains some of the biggest volcanoes in the solar system and dominates the topography of Mars. Earth, twice the diameter and 10 times more massive than Mars, has no equivalent dominating feature. Tharsis's bulk creates a bulge on the opposite side of the planet and a depression halfway between. This explains why estimates of the volume of water the northern plains could hold based on today's topography are twice what the new study estimates based on the topography 4 billion years ago.
New hypothesis supplants old
Manga, who models the internal heat flow of Mars, such as the rising plumes of molten rock that erupt into volcanoes at the surface, tried to explain the irregular shorelines of the plains of Mars 11 years ago with another theory. He and former graduate student Taylor Perron suggested that Tharsis, which was then thought to have originated at far northern latitudes, was so massive that it caused the spin axis of Mars to move several thousand miles south, throwing off the shorelines.

Since then, however, others have shown that Tharsis originated only about 20 degrees above the equator, nixing that theory. But Manga and Citron came up with another idea, that the shorelines could have been etched as Tharsis was growing, not afterward. The new theory also can account for the cutting of valley networks by flowing water at around the same time.

"This is a hypothesis," Manga emphasized. "But scientists can do more precise dating of Tharsis and the shorelines to see if it holds up."

NASA's next Mars lander, the InSight mission (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport), could help answer the question. Scheduled for launch in May, it will place a seismometer on the surface to probe the interior and perhaps find frozen remnants of that ancient ocean, or even liquid water.

More information: Robert I. Citron et al, Timing of oceans on Mars from shoreline deformation, Nature (2018). DOI: 10.1038/nature26144

Provided by: University of California - Berkeley

# data[].attributes.attachment_link.title
Mars' oceans formed early, possibly aided by massive volcanic eruptions

# data[].attributes.attachment_link.description
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million years earlier and were not as deep as once thought.

# data[].attributes.attachment_link.readable_text
Usando dados de radar pesquisadores encontraram evidências de uma era do gelo registrada nos depósitos polares de Marte da qual o planeta estaria emergindo. eras do gelo em Marte são causadas por processos semelhantes aos responsáveis por eras do gelo na Terra, ou seja, mudanças cíclicas de longo prazo na órbita e inclinação do planeta, o que afeta a quantidade de radiação solar que Marte recebe em cada latitude.

Com auxílio de dados de radar recolhidos pela Mars Reconnaissance Orbiter da NASA, uma equipe de cientistas liderada pela Southwest Research Institute encontraram evidências de uma era do gelo registrada nos depósitos polares de Marte.

"Nós encontramos uma taxa de acumulação acelerada de gelo nos pontos mais altos entre 100 e 300 metros da calota polar", afirma o Dr. Isaac Smith, pesquisador de pós-doutorado na Southwest Research e principal autor de um artigo publicado na edição em 27 de maio na revista Science. "O volume e a espessura do gelo corresponde a previsões do modelo feito no início dos anos 2000. Observações de radar das calotas de gelo fornecem uma história detalhada da acumulação do gelo e da erosão associadas a essas alterações climáticas."

Ciclos e a era do gelo em marte

Tal como a Terra dos dias de hoje Marte experimenta ciclos anuais e sazonais de rotação, bem como ciclos mais longos, que influenciam a distribuição de gelo por todo o planeta. No entanto, estes ciclos mais longos podem ser mais drásticos em Marte do que são na Terra. Isso acontece, pois a inclinação de Marte muda radicalmente - em até cerca de 60 graus - em escalas de tempo de centenas de milhares a milhões de anos. Para efeito de comparação, a inclinação da Terra varia apenas cerca de 2 graus durante o mesmo período. Em Marte, esta maior variabilidade determina a quantidade de luz solar que atinge um determinado local sobre a superfície e, assim, a estabilidade do gelo em todas as latitudes.

"Porque o clima em Marte flutua com oscilações maiores na inclinação axial, e o gelo se distribui de forma diferente em cada ciclo, Marte seria substancialmente diferente no passado do que é agora", sugere Smith. "Além disso, porque Marte não tem oceanos, atualmente, representa uma espécie 'laboratório intocado' para compreender a ciência do clima aqui na Terra."

Medidas detalhadas da espessura do gelo mostraram que cerca de 87.000 quilômetros cúbicos de gelo têm se acumulado nos pólos desde o fim da última era glacial, cerca de 370.000 anos atrás; a maioria do material acumulado no pólo norte marciano. Tal volume que é equivalente a uma camada de 60 cm, se espalhou uniformemente em toda a superfície. Estes resultados fornecem um meio para entender a história de acumulo nos depósitos polares relacionados aos movimentos de Marte, como a excentricidade orbital, inclinação axial, e rotação em torno do Sol. Os resultados irão apoiar os esforços de modelagem para entender o clima marciano, observando o movimento do gelo dos pólos para latitudes médias durante os ciclos climáticos.

"Estudar o gelo em Marte também é importante para o futuro da exploração humana do planeta vermelho", afirma Smith. "A água será um recurso crítico para um posto avançado marciano no futuro."

Referências:

SMITH, I. B. et al. An ice age recorded in the polar deposits of Mars. Science, [s.l.], v. 352, n. 6289, p.1075-1078, 26 maio 2016. American Association for the Advancement of Science (AAAS). http://dx.doi.org/10.1126/science.aad6968.

# data[].attributes.attachment_link.title
Evidências apontam que marte está numa "Era do gelo"

# data[].attributes.attachment_link.description
Usando dados de radar pesquisadores encontraram evidências de uma era do gelo registrada nos depósitos polares de Marte da qual o planeta estaria emergindo. eras do gelo em Marte são causadas por processos semelhantes aos responsáveis por eras do gelo na Terra, ou seja, mudanças cíclicas de longo prazo na órbita e inclinação do planeta, o que afeta a quantidade de radiação solar que Marte recebe em cada latitude.

# data[].attributes.attachment_link.readable_text
Sabemos que duas vezes por dia o mar avança e recua nas praias esse fenômeno é chamado maré. Mas como se formam as marés? Isaac Newton já nos explicou isso. Tal fenômeno é causa pela gravidade lunar que atua com mais força sobre os oceanos que estão voltados para a Lua, com menor intensidade sobre o centro da terra e com intensidade ainda menor sobre os oceanos que não estão voltados para a Lua. Por conseguinte, os oceanos deformam em duas direções: de um lado, porque a água é puxada no sentido de se afastar da Terra e, de outro, porque a Terra é afastada da água.

As marés, a lua e a gravidade

A causa das marés não é exatamente a gravidade, mas sim as diferenças na gravidade. Como a Terra completa uma volta a cada 24 horas, a onda das marés percorre a Terra provocando maré duas vezes por dia, elas ocorrem também na parte rochosa da Terra, entretanto eles são muito menores, pois a rocha é muito mais rígida.

O vídeo abaixo em time-lapse mostra a maré alta se formando na praia de Saint Malo.

Maré causada pelo sol e a lua.

O acelerador de partículas, Large Hadron Collider, instalado em Genebra, se expande e encolhe à medida que a Lua estica, e espreme o anel de 27 quilômetros do acelerador de partículas. O Sol também cria marés, embora com apenas um terço do tamanho. Quando o Sol e a Lua puxam na mesma direção, temos as marés mais altas.

A Terra também gera marés na Lua 81 vezes mais poderosas, uma vez que a Terra tem uma massa 81 vezes maior que a da Lua. Isso cria tremores na Lua e erupções ocasionais de gás. Com o tempo, essa força de marés reduziu a rotação da Lua, de modo que ela essencialmente antém uma mesma face voltada para a Terra; A Lua completa uma volta sobre o seu eixo a cada 28 dias! sendo que é o mesmo tempo que leva para completar uma volta em torno da Terra. Entretanto, todos os lados da Lua recebem luz do sol: à medida que a lua orbita a Terra partes diferentes são iluminadas pelo Sol, resultando nas "fases" que nós vemos.

O movimento das marés faz com que a Terra vá perdendo energia, fazendo com que ela gire cada vez mais devagar e também com que a Lua se afaste da Terra.

# data[].attributes.attachment_link.title
Maré | O que é, e como se forma o fenômeno das marés

# data[].attributes.attachment_link.description
Sabemos que duas vezes por dia o mar avança e recua nas praias esse fenômeno é chamado maré. Mas como se formam as marés? Isaac Newton já nos explicou isso.

# data[].attributes.attachment_link.title
When rotated at a 'magic angle,' graphene sheets can form an insulator or a superconductor

# data[].attributes.attachment_link.description
It's hard to believe that a single material can be described by as many superlatives as graphene can. Since its discovery in 2004, scientists have found that the lacy, honeycomb-like sheet of carbon atoms - essentially the ...

# data[].attributes.headline
"Oumuamua" provavelmente veio de um sistema solar com duas estrelas!

# data[].attributes.subject
"Oumuamua" provavelmente veio de um sistema solar com duas estrelas!

# data[].attributes.attachment_link.title
'Oumuamua likely came from a binary star system

# data[].attributes.attachment_link.description
New research finds that 'Oumuamua, the rocky object identified as the first confirmed interstellar asteroid, very likely came from a binary star system.

# data[].attributes.headline
Cientistas detectam ecos de rádio de um buraco negro alimentando uma estrela

# data[].attributes.subject
Cientistas detectam ecos de rádio de um buraco negro alimentando uma estrela

# data[].attributes.attachment_link.title
Scientists detect radio echoes of a black hole feeding on a star

# data[].attributes.attachment_link.description
On Nov. 11, 2014, a global network of telescopes picked up signals from 300 million light years away that were created by a tidal disruption flare-an explosion of electromagnetic energy that occurs when a black hole rips ...

# data[].attributes.headline
O tesla enviado para o espaco pode conter batérias terrestres!

# data[].attributes.subject
O tesla enviado para o espaco pode conter batérias terrestres!

# data[].attributes.attachment_link.title
Tesla in space could carry bacteria from Earth

# data[].attributes.attachment_link.description
A red Tesla convertible hitched a ride to space with a SpaceX rocket in early February, bringing with it what may be the largest load of earthly bacteria to ever enter space.

# data[].attributes.attachment_link.readable_text
This illustration shows 3 steps astronomers used to measure the universe's expansion rate (Hubble constant) to an unprecedented accuracy, reducing the total uncertainty to 2.3 percent. The measurements streamline and strengthen the construction of the cosmic distance ladder, which is used to measure accurate distances to galaxies near to and far from Earth. The latest Hubble study extends the number of Cepheid variable stars analyzed to distances of up to 10 times farther across our galaxy than previous Hubble results. Credit: NASA, ESA, A. Feild (STScI), and A. Riess (STScI/JHU)

Astronomers have used NASA's Hubble Space Telescope to make the most precise measurements of the expansion rate of the universe since it was first calculated nearly a century ago. Intriguingly, the results are forcing astronomers to consider that they may be seeing evidence of something unexpected at work in the universe.

That's because the latest Hubble finding confirms a nagging discrepancy showing the universe to be expanding faster now than was expected from its trajectory seen shortly after the big bang. Researchers suggest that there may be new physics to explain the inconsistency.

"The community is really grappling with understanding the meaning of this discrepancy," said lead researcher and Nobel Laureate Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University, both in Baltimore, Maryland.

Riess's team, which includes Stefano Casertano, also of STScI and Johns Hopkins, has been using Hubble over the past six years to refine the measurements of the distances to galaxies, using their stars as milepost markers. Those measurements are used to calculate how fast the universe expands with time, a value known as the Hubble constant. The team's new study extends the number of stars analyzed to distances up to 10 times farther into space than previous Hubble results.

But Riess's value reinforces the disparity with the expected value derived from observations of the early universe's expansion, 378,000 years after the big bang - the violent event that created the universe roughly 13.8 billion years ago. Those measurements were made by the European Space Agency's Planck satellite, which maps the cosmic microwave background, a relic of the big bang. The difference between the two values is about 9 percent. The new Hubble measurements help reduce the chance that the discrepancy in the values is a coincidence to 1 in 5,000.

Planck's result predicted that the Hubble constant value should now be 67 kilometers per second per megaparsec (3.3 million light-years), and could be no higher than 69 kilometers per second per megaparsec. This means that for every 3.3 million light-years farther away a galaxy is from us, it is moving 67 kilometers per second faster. But Riess's team measured a value of 73 kilometers per second per megaparsec, indicating galaxies are moving at a faster rate than implied by observations of the early universe.

The Hubble data are so precise that astronomers cannot dismiss the gap between the two results as errors in any single measurement or method. "Both results have been tested multiple ways, so barring a series of unrelated mistakes," Riess explained, "it is increasingly likely that this is not a bug but a feature of the universe."
Explaining a Vexing Discrepancy
Riess outlined a few possible explanations for the mismatch, all related to the 95 percent of the universe that is shrouded in darkness. One possibility is that dark energy, already known to be accelerating the cosmos, may be shoving galaxies away from each other with even greater - or growing - strength. This means that the acceleration itself might not have a constant value in the universe but changes over time in the universe. Riess shared a Nobel Prize for the 1998 discovery of the accelerating universe.

Another idea is that the universe contains a new subatomic particle that travels close to the speed of light. Such speedy particles are collectively called "dark radiation" and include previously known particles like neutrinos, which are created in nuclear reactions and radioactive decays. Unlike a normal neutrino, which interacts by a subatomic force, this new particle would be affected only by gravity and is dubbed a "sterile neutrino."

Yet another attractive possibility is that dark matter (an invisible form of matter not made up of protons, neutrons, and electrons) interacts more strongly with normal matter or radiation than previously assumed.

Any of these scenarios would change the contents of the early universe, leading to inconsistencies in theoretical models. These inconsistencies would result in an incorrect value for the Hubble constant, inferred from observations of the young cosmos. This value would then be at odds with the number derived from the Hubble observations.

Riess and his colleagues don't have any answers yet to this vexing problem, but his team will continue to work on fine-tuning the universe's expansion rate. So far, Riess's team, called the Supernova H0 for the Equation of State (SH0ES), has decreased the uncertainty to 2.3 percent. Before Hubble was launched in 1990, estimates of the Hubble constant varied by a factor of two. One of Hubble's key goals was to help astronomers reduce the value of this uncertainty to within an error of only 10 percent. Since 2005, the group has been on a quest to refine the accuracy of the Hubble constant to a precision that allows for a better understanding of the universe's behavior.

These Hubble Space Telescope images showcase 2 of the 19 galaxies analyzed in a project to improve the precision of the universe's expansion rate, a value known as the Hubble constant. The color-composite images show NGC 3972 (left) and NGC 1015 (right), located 65 million light-years and 118 million light-years, respectively, from Earth. The yellow circles in each galaxy represent the locations of pulsating stars called Cepheid variables. Credit: NASA, ESA, A. Riess (STScI/JHU)

Building a Strong Distance Ladder
The team has been successful in refining the Hubble constant value by streamlining and strengthening the construction of the cosmic distance ladder, which the astronomers use to measure accurate distances to galaxies near to and far from Earth. The researchers have compared those distances with the expansion of space as measured by the stretching of light from receding galaxies. They then have used the apparent outward velocity of galaxies at each distance to calculate the Hubble constant.

But the Hubble constant's value is only as precise as the accuracy of the measurements. Astronomers cannot use a tape measure to gauge the distances between galaxies. Instead, they have selected special classes of stars and supernovae as cosmic yardsticks or milepost markers to precisely measure galactic distances.

Among the most reliable for shorter distances are Cepheid variables, pulsating stars that brighten and dim at rates that correspond to their intrinsic brightness. Their distances, therefore, can be inferred by comparing their intrinsic brightness with their apparent brightness as seen from Earth.

Astronomer Henrietta Leavitt was the first to recognize the utility of Cepheid variables to gauge distances in 1913. But the first step is to measure the distances to Cepheids independent of their brightness, using a basic tool of geometry called parallax. Parallax is the apparent shift of an object's position due to a change in an observer's point of view. This technique was invented by the ancient Greeks who used it to measure the distance from Earth to the Moon.

The latest Hubble result is based on measurements of the parallax of eight newly analyzed Cepheids in our Milky Way galaxy. These stars are about 10 times farther away than any studied previously, residing between 6,000 light-years and 12,000 light-years from Earth, making them more challenging to measure. They pulsate at longer intervals, just like the Cepheids observed by Hubble in distant galaxies containing another reliable yardstick, exploding stars called Type Ia supernovae. This type of supernova flares with uniform brightness and is brilliant enough to be seen from relatively farther away. Previous Hubble observations studied 10 faster-blinking Cepheids located 300 light-years to 1,600 light-years from Earth.
Scanning the Stars
To measure parallax with Hubble, the team had to gauge the apparent tiny wobble of the Cepheids due to Earth's motion around the Sun. These wobbles are the size of just 1/100 of a single pixel on the telescope's camera, which is roughly the apparent size of a grain of sand seen 100 miles away.

Therefore, to ensure the accuracy of the measurements, the astronomers developed a clever method that was not envisioned when Hubble was launched. The researchers invented a scanning technique in which the telescope measured a star's position a thousand times a minute every six months for four years.

The team calibrated the true brightness of the eight slowly pulsating stars and cross-correlated them with their more distant blinking cousins to tighten the inaccuracies in their distance ladder. The researchers then compared the brightness of the Cepheids and supernovae in those galaxies with better confidence, so they could more accurately measure the stars' true brightness, and therefore calculate distances to hundreds of supernovae in far-flung galaxies with more precision.

Another advantage to this study is that the team used the same instrument, Hubble's Wide Field Camera 3, to calibrate the luminosities of both the nearby Cepheids and those in other galaxies, eliminating the systematic errors that are almost unavoidably introduced by comparing those measurements from different telescopes.

"Ordinarily, if every six months you try to measure the change in position of one star relative to another at these distances, you are limited by your ability to figure out exactly where the star is," Casertano explained. Using the new technique, Hubble slowly slews across a stellar target, and captures the image as a streak of light. "This method allows for repeated opportunities to measure the extremely tiny displacements due to parallax," Riess added. "You're measuring the separation between two stars, not just in one place on the camera, but over and over thousands of times, reducing the errors in measurement."

The team's goal is to further reduce the uncertainty by using data from Hubble and the European Space Agency's Gaia space observatory, which will measure the positions and distances of stars with unprecedented precision. "This precision is what it will take to diagnose the cause of this discrepancy," Casertano said.

Provided by: NASA's Goddard Space Flight Center

# data[].attributes.attachment_link.title
Improved Hubble yardstick gives fresh evidence for new physics in the universe

# data[].attributes.attachment_link.description
Astronomers have used NASA's Hubble Space Telescope to make the most precise measurements of the expansion rate of the universe since it was first calculated nearly a century ago. Intriguingly, the results are forcing astronomers to consider that they may be seeing evidence of something unexpected at work in the universe.

# data[].attributes.attachment_link.description
Beakus were commissioned to create three animated films that explain key concepts about our universe, with humour helping to explain the 'almost' unexplainable! Director Amaël Isnard also designed the films. In 'How Do We Know How Old The Sun Is?'

# data[].attributes.headline
O que se encontra dentro de um buraco negro?

# data[].attributes.subject
O que se encontra dentro de um buraco negro?

# data[].attributes.attachment_link.description
Beakus were commissioned to create three animated films that explain key concepts about our universe, with humour helping to explain the 'almost' unexplainable! Director Amaël Isnard also designed the films. In 'What's Inside A Black Hole?' ROG astronomer Rad explains where black holes come from, how we know they're there and the strange effects they have on surrounding matter.

# data[].attributes.attachment_link.description
Beakus were commissioned to create three animated films that explain key concepts about our universe, with humour helping to explain the 'almost' unexplainable! Director Amaël Isnard also designed the films. In 'How Big Is The Universe?'

# data[].attributes.attachment_link.description
Use your smart phone to explore Mars with me in 360 degrees. #FromWhereIStand