Questões de Vestibular

Astronomers have taken the first ever image of a black hole, which is located in a distant galaxy. It measures 40 billion km across - three million times the size of the Earth - and has been described by scientists as "a monster".

The black hole is 500 million trillion km away and was photographed by a network of eight telescopes across the world It was captured by the Event Horizon Telescope (EHT), a network of eight linked telescopes. 

Prof Heino Falcke, of Radboud University in the Netherlands, who proposed the experiment, told BBC News that the black hole was found in a galaxy called M87.

"What we see is larger than the size of our entire Solar System," he said.

"It has a mass 6.5 billion times that of the Sun. And it is one of the heaviest black holes that we think exists. It is an absolute monster, the heavyweight champion of black holes in the Universe."

The image shows an intensely bright "ring of fire", as Prof Falcke describes it, surrounding a perfectly circular dark hole. The bright halo is caused by superheated gas falling into the hole. The light is brighter than all the billions of other stars in the galaxy combined - which is why it can be seen at such distance from Earth.

The edge of the dark circle at the centre is the point at which the gas enters the black hole, which is an object that has such a large gravitational pull, not even light can escape.

The image matches what theoretical physicists and indeed, Hollywood directors, imagined black holes would look like, according to Dr Ziri Younsi, of University College London - who is part of the EHT collaboration.

"Although they are relatively simple objects, black holes raise some of the most complex questions about the nature of space and time, and ultimately of our existence," he said.

"It is remarkable that the image we observe is so similar to that which we obtain from our theoretical calculations. So far, it looks like Einstein is correct once again."

But having the first image will enable researchers to learn more about these mysterious objects. They will be keen to look out for ways in which the black hole departs from what's expected in physics. No-one really knows how the bright ring around the hole is created. Even more intriguing is the question of what happens when an object falls into a black hole.

Source: www.bbc.com/news/science-environment-47873592

    People who exercise five days a week for 30 minutes significantly reduce their risk of dying early and of developing heart disease, even if a sports club or gym is not an option, according to a new international study.
    Tracking 130,000 people in 17 countries, both rich and poor, the study found that whether it’s going to the gym, walking to work, or tackling household chores like laundry or gardening, being physically active extends life and reduces illness. The researchers, led by Scott Lear, a heart specialist at St Paul’s Hospital in Canada, also found a so-called dose response: The more people exercise, the greater the reductions are in their risks of getting heart disease or dying early. The study found “no ceiling effect”, the researchers said, and “no risks associated with extremely high levels of physical activity,” defined as more than 2,500 minutes, or more than 41 hours, per week.
    Cardiovascular disease is the world’s leading cause of death and a major economic burden in treatment and care for those who develop it. It killed 9.48 million people globally in 2016.
    “Walking for as little as 30 minutes most days of the week has a substantial benefit, and higher physical activity is associated with even lower risks,” Lear said in a comment about the findings, published on Friday in The Lancet medical journal. He also noted that some measures to prevent or treat heart disease, such as taking medicines or eating more fruit and vegetables, can be unaffordable for the world’s poorest people. Yet walking is free and brings substantial health gains.
    The World Health Organization recommends that adults aged 18 to 64 do at least 150 minutes of moderate-intensity aerobic physical activity throughout each week, as well as muscle strengthening exercises at least two days a week. But experts estimate almost a quarter of the world’s people do not reach these guideline levels.
    Lear’s team said their study findings suggest that if the entire population were to meet the guidelines, one in 12 of the world’s premature deaths would be averted and 4.6 percent of heart disease cases prevented.

KELLAND, Kate. Disponível em:<http://www.reuters.com/article/us-puretech-health-gelesis-study/puretechs-gelesis-says-obesity-drug-achieved-weight-loss-in-study-idUSKCN1C00PD> . Acesso em 25/09/2017. Texto Adaptado.