Space Science Episode 2: What it takes to become an Astronaut To look at the Earth from outer space - who doesn’t dream about that view? But is being an astronaut really a dream job? Are the years of training and hardships each candidate must be willing to endure really worth it? Prof. Dr. Ulrich Walter, astronaut and space expert, knows what he’s talking about because he did it. In this episode of Space Science, he shows what demands are asked of today's applicants and recounts stories of legendary astronauts.

Space Science Episode 1: The weightless person - life and love in space For 40 years now, people have been living in outer space - first on the space stations Salyut and Skylab, today on the ISS, and perhaps, soon, in a spaceship to Mars. What is an astronaut’s life like, and what will it be like in the future? What challenges do showering, eating and sleeping bring? Astronaut Prof. Dr. Ulrich Walter explains in "Space Science" how it all works, how these challenges in space are met and overcome, in everyday life, work and even love.

Artificial gravity is a concept that is ubiquitous in our science fiction yet elusive in our space program. Why is this? And how could we develop artificial gravity soon? In a Cool Worlds special, this video essay goes in depth on the topic discussing why centrifuges are the most plausible solution and early ideas on the topic. Join us a journey from Einstein's equivalence principle, to O'Neill Cylinders and Stanford Tori; from Coriolis forces to near-term experiments. Grab a cup of a tea and enjoy.

Very few people have been lucky enough to see our home planet from Space, but thanks to the incredible spacecraft that are exploring or have already explored neighbouring celestial objects, we get to view amazing footage of the Earth from all over the solar system. So what does Earth look like from deep space?

Can’t get enough of Earth? Then this is for you: an extended playback of Ultra High Definition views of Planet Earth, captured by NASA astronaut Jeff Williams during his mission on the International Space Station in 2016. You’ll see the French Riviera and the Sahara Desert, cross North America from Texas all the way to Canada, and more—this is your source for the view of your home planet from 250 miles up!

These high-res time-lapse sequences captured by astronauts aboard the International Space Station give us a beautiful and clear view of some well-known coastlines and countries around the world. Get a good look at England, France, Italy, Egypt, Algeria, Tunisia, Greece, the island of Crete, Taiwan, South Korea, Japan, the United States, Mexico, Ecuador, Peru, Chile, Argentina, Cuba, and more. We've attempted to show as many countries as we would, but inevitably we've left many out. Please write to the the astronaut photography office at NASA's Johnson Space Center to request inclusion in this amazing series of sequences.

Планетата Земја, видена од вселената - Macedonian Երկիր մոլորակը տիեզերքից - Armenian Planeta Terra visto do espaço - Português (Brasil) Ο Πλανήτης ΓΗ από το Διάστημα - Ελληνικά (Hellenic Language) Il Pianeta Terra visto dallo spazio - Italian Pamântul văzut din spațiu - Romanian / Moldavian language Космостан қарағандағы Жер ғаламшары - kazakh Yerin kosmosdan görünüşü - Azerbaijani Yerin uzaydan görünüşü - Azerbaijani Ang Daigdig mula sa kalawakan - Filipino/Tagalog Jorden fra rommet - Norwegian Jorden set fra rummet - Danish პლანეტა დედამიწის შეხედვა კოსმოსიდან - Georgian Planeta terra visto do espaço - Português Planeta Terra visto do Espaço - Brazilian portuguese ji ezman dîmen ê Erd ê (Kurdish) Planet Erde vom Weltraum aus betrachtet - (German) maa avaruudesta nähtynä - (Finnish) uzaydan dünyanın görünümü (Turkish) Planeti Toke pare nga hapesira - Shqip (Albanian) මිහිතලය අභ්‍යවකාශයේ සිට පෙනෙන ආකාරය. - (Sinhalese, Sri Lanka) эх дэлхий сансараас - (Mongolian) Planeti Toke pare nga hapesira - Shqip (Albanian) ดาวเคราะห์โลกเมื่อมองจากอวกาศ (Thai) 우주에서 본 지구 - (Korean) "Земля з космосу" - (Ukrainian) Planeta Pamant vazuta din spatiu - (Romanian) A Föld az Űrből - (Hungarian) "Ziemia widziana z kosmosu" - (Polish) Земята от космоса - (Bulgarian) "Планета Земля из космоса" - (Russian) "Zeme ir redzama no kosmosa" - (Latvian) meeraha dhulka hawada laga arko - (Somali) An Domhain ó spás - (Irish) "de Aarde gezien vanuit de ruimte" - Dutch رؤية كوكب الأرض من الفضاء. - Arabic "Terra vista do espaço" Terra vista des de l'espai "Earth seen from space" "la terre vue de l'espace" "la tierra desde el espacio" "El planeta Tierra visto desde el espacio" (spanish) "terra vista dallo spazio" โลกดาวเคราะห์เห็นได้จากพื้นที่ يبلغ حجم القمر ربع حجم الأرض ولا يوجد فيه لا هواء ولا ماء ولا حياة. 從太空中看到地球 从太空中看到地球 宇宙から見た地球 Zemlje vidi iz svemira Zemlja iz svemira Země z vesmíru Earth séð frá geimnum પૃથ્વી જગ્યા માંથી જોઇ Jorden set fra rummet Maa kosmosest vaadatuna Maan avaruudesta nähtynä Γη από το διάστημα ഭൂമി ബഹിരാകാശത്തില്‍ നിന്നും כדור הארץ כפי שנראה מהחלל ಭೂಮಿಯ ಜಾಗವನ್ನು ಕಂಡಂತೆ पृथ्वी अंतरिक्ष से देखा Aarde gezien vanuit de ruimte Bumi dilihat dari angkasa Jörð séð frá geimnum Uzaydan Dünyaya Bakış 지구는 우주에서 본 Žemės vaizdas iš kosmoso Zemes redzams no kosmosu Jorden sett fra verdensrommet Pământ văzut din spaţiu Zemlji videl iz vesolja Jorden sedd från rymden Dünya, uzayın görülen Yer kosmik göründüyü Trái đất nhìn từ không gian Terra vista dallo spazio كوكب الارض كما يظهر من الفضاء " زمین از فضا دیده می شود زمین کی خلا سے دیکھا منظر الأرض من الفضاء (Arabic) Gweld Ddaear o'r gofod பூமியை விண்வெளியில் இருந்து பார்க்கும் โลกเห็นได้จากพื้นที่ Kuonekana duniani kutoka nafasi Земље види из свемира Երկրի երեւում է տիեզերքից Dinja tidher mill-ispazju Latè te wè li nan lespas Земјата се гледа од вселената "blue marble"

The International Space Station’s High Definition Earth Viewing (HDEV) experiment is an external camera platform located on the Columbus module of the space station. In addition to providing beautiful views of Earth, one of the goals of HDEV is to monitor the longevity and quality of its image sensors in the space environment. HDEV operations began April 30, 2014 and only a single bad pixel has been identified. Testing new engineering processes and camera system longevity expanded into having avid Earth-viewing followers and educational activities. To date, HDEV has reached over 300 million total views on UStream.

How did the universe come into existence? The singular answer that pops in the heads of pretty much everyone on the face of the earth is “The Big Bang Theory.” It does not take a scientist to be aware of this term, with a lot of the present generation having a very (note the term “very”) brief understanding of the big bang theory thanks to the opening theme of the popular television series of the same name. For those of you who have forgotten (we understand it isn’t the easiest thing to remember), the theory states that the universe started as an infinitely small, dense point called a singularity. All of a sudden, within a trillionth of a second, it expanded rapidly at a rate faster than the speed of light forming what we know as the universe today. The universe is unbelievably vast and carries an enigma of the same magnitude making any theory related to it, only ever partially correct. While the big bang theory is the most widely accepted one of them all, scientists have always known that it certainly isn’t entirely accurate. So what caused the birth of the known universe? A possibility is being considered where a singularity probably never existed in which case the universe grew at a far more comprehensible speed than originally assumed, relatively speaking. Relative to what you ask? It is now believed that expansion had happened before the big bang, thus proving it to not be the starting point. Before we move on, let us understand the justification leading to the inception of the big bang theory. This theory was proposed by a priest and astronomer named Georges LeMaître in the 1920s when scientists realized that the galaxies at the farthest points were moving away from us faster than the closest ones. This suggested the possibility that it’s not the galaxies that are moving, but the universe that’s expanding. From an expansion point of view, it is quite easy to visualize an expanding object to have been at its smallest at some point in time. The same was applied to the universe, rising the phenomenon of a singularity to have been the most probable starting point. Building on the theory of expansion, we understand that light stretches as well. The galaxies at the farthest end are red-shifted, meaning their light wavelengths have stretched out and headed for the red, lower-energy end of the electromagnetic spectrum. A very important conclusion that can be drawn from this is the fact that everything started out with higher energy in the past making the universe awfully hot at that point of time. Many examples exist in this very universe today that substantiate the same. To name a few, let us talk about the plasma soup that created the young universe. We also have a fairly good understanding of what those particles have merged into, which coincides with the exact ratio of particles we see in the universe today. We also see traces of proof in the form of the weak, super-stretched leftover radiation that makes up the cosmic microwave background. Everything seems to be falling into place, right? Well, not really, as is with anything to do with this mystery of a universe. Let us now dive into the deviations that question the accuracy of this theory. The cosmic microwave background proposes the idea that the universe is flat, which contradicts with the whole big bang expansion theory calling for the universe to be curved. Secondly, everything in the universe seems to about the same temperature. Finally, it is believed that the proposed big bang should have produced mega high-energy particles called magnetic monopoles but none of them has been found or traced yet. These deviations from the popular theory lead to the proposal of the inflation theory that discusses the birth of the universe to be a result of the fluctuations in the void of space. The basis behind this new theory is a quantity called vacuum energy. We understand that no matter of radiation existed before the big bang as per the inflation theory. That being said, a vacuum is still full of energy as a result of the pairs of quantum particles that constantly blink in and out of existence. This resultant energy led to the exponential expansion of the universe enlarging it by a factor close to 1026 in a fraction of a second. This expansion caused fluctuations in the vacuum energy leaving the fabric of space uneven. This essentially means that random spots existed where the energy density was slightly higher or slightly lower than average. Eventually, all that energy decayed into matter and radiation. The inflation theory fixes a lot of the holes in the big bang theory. It works with a flat universe and the rate at which it happened allows for uniformity in temperature (one of the variations in the big bang theory) as it suggests the possibility that every point in the universe might have once been in contact. Inflation also says that magnetic monopoles may have existed prior to expansion, but their density would have plummeted to insignificant levels afterwards. What’s more, the fluctuations in energy provide an excellent theory as to how galaxies and stars are formed. Humanity, as we know it today, came into spectacular existence due to those seemingly random clusters of energy, so before we look into the big bang as the mother of all existence, we might want to look closely into the hidden dawn of the universe.

The Big Bang Theory is the leading explanation about how the universe began. At its simplest, it says the universe as we know it started with a small singularity, then inflated over the next 13.8 billion years to the cosmos that we know today. Because current instruments don't allow astronomers to peer back at the universe's birth, much of what we understand about the Big Bang Theory comes from mathematical formulas and models. Astronomers can, however, see the "echo" of the expansion through a phenomenon known as the cosmic microwave background. While the majority of the astronomical community accepts the theory, there are some theorists who have alternative explanations besides the Big Bang — such as eternal inflation or an oscillating universe. The phrase "Big Bang Theory" has been popular among astrophysicists for decades, but it hit the mainstream in 2007 when a comedy show with the same name premiered on CBS. The show follows the home and academic life of several researchers (including an astrophysicist). The first second, and the birth of light In the first second after the universe began, the surrounding temperature was about 10 billion degrees Fahrenheit (5.5 billion Celsius), according to NASA. The cosmos contained a vast array of fundamental particles such as neutrons, electrons and protons. These decayed or combined as the universe got cooler. This early soup would have been impossible to look at, because light could not carry inside of it. "The free electrons would have caused light (photons) to scatter the way sunlight scatters from the water droplets in clouds," NASA stated. Over time, however, the free electrons met up with nuclei and created neutral atoms. This allowed light to shine through about 380,000 years after the Big Bang. This early light — sometimes called the "afterglow" of the Big Bang — is more properly known as the cosmic microwave background (CMB). It was first predicted by Ralph Alpher and other scientists in 1948, but was found only by accident almost 20 years later. [Images: Peering Back to the Big Bang & Early Universe] Arno Penzias and Robert Wilson, both of Bell Telephone Laboratories in Murray Hill, New Jersey, were building a radio receiver in 1965 and picking up higher-than-expected temperatures, according to NASA. At first, they thought the anomaly was due to pigeons and their dung, but even after cleaning up the mess and killing pigeons that tried to roost inside the antenna, the anomaly persisted. Simultaneously, a Princeton University team (led by Robert Dicke) was trying to find evidence of the CMB, and realized that Penzias and Wilson had stumbled upon it. The teams each published papers in the Astrophysical Journal in 1965. Determining the age of the universe The cosmic microwave background has been observed on many missions. One of the most famous space-faring missions was NASA's Cosmic Background Explorer (COBE) satellite, which mapped the sky in the 1990s. Several other missions have followed in COBE's footsteps, such as the BOOMERanG experiment (Balloon Observations of Millimetric Extragalactic Radiation and Geophysics), NASA's Wilkinson Microwave Anisotropy Probe (WMAP) and the European Space Agency's Planck satellite. Planck's observations, first released in 2013, mapped the background in unprecedented detail and revealed that the universe was older than previously thought: 13.82 billion years old, rather than 13.7 billion years old. [Related: How Old is the Universe?] (The research observatory's mission is ongoing and new maps of the CMB are released periodically.) The maps give rise to new mysteries, however, such as why the Southern Hemisphere appears slightly redder (warmer) than the Northern Hemisphere. The Big Bang Theory says that the CMB would be mostly the same, no matter where you look. Examining the CMB also gives astronomers clues as to the composition of the universe. Researchers think most of the cosmos is made up of matter and energy that cannot be "sensed" with conventional instruments, leading to the names dark matter and dark energy. Only 5 percent of the universe is made up of matter such as planets, stars and galaxies. Gravitational waves controversy While astronomers could see the universe's beginnings, they've also been seeking out proof of its rapid inflation. Theory says that in the first second after the universe was born, our cosmos ballooned faster than the speed of light. That, by the way, does not violate Albert Einstein's speed limit since he said that light is the maximum anything can travel within the universe. That did not apply to the inflation of the universe itself. In 2014, astronomers said they had found evidence in the CMB concerning "B-modes," a sort of polarization generated as the universe got bigger and created gravitational waves. The team spotted evidence of this using an Antarctic telescope called "Background Imaging of Cosmic Extragalactic Polarization", or BICEP2. "We're very confident that the signal that we're seeing is real, and it's on the sky," lead researcher John Kovac, of the Harvard-Smithsonian Center for Astrophysics, told Space.com in March 2014. But by June, the same team said that their findings could have been altered by galactic dust getting in the way of their field of view. "The basic takeaway has not changed; we have high confidence in our results," Kovac said in a press conference reported by the New York Times. "New information from Planck makes it look like pre-Planckian predictions of dust were too low," he added. The results from Planck were put online in pre-published form in September. By January 2015, researchers from both teams working together "confirmed that the Bicep signal was mostly, if not all, stardust," the New York Times said in another article. Separately, gravitational waves have been confirmed when talking about the movements and collisions of black holes that are a few tens of masses larger than our sun. These waves have been detected multiple times by the Laser Interferometer Gravitational-Wave Observatory (LIGO) since 2016. As LIGO becomes more sensitive, it is anticipated that discovering black hole-related gravitational waves will be a fairly frequent event. Faster inflation, multiverses and charting the start The universe is not only expanding, but getting faster as it inflates. This means that with time, nobody will be able to spot other galaxies from Earth, or any other vantage point within our galaxy. "We will see distant galaxies moving away from us, but their speed is increasing with time," Harvard University astronomer Avi Loeb said in a March 2014 Space.com article. "So, if you wait long enough, eventually, a distant galaxy will reach the speed of light. What that means is that even light won't be able to bridge the gap that's being opened between that galaxy and us. There's no way for extraterrestrials on that galaxy to communicate with us, to send any signals that will reach us, once their galaxy is moving faster than light relative to us." Some physicists also suggest that the universe we experience is just one of many. In the "multiverse" model, different universes would coexist with each other like bubbles lying side by side. The theory suggests that in that first big push of inflation, different parts of space-time grew at different rates. This could have carved off different sections — different universes — with potentially different laws of physics. "It's not impossible, so I think there's still certainly research that needs to be done. But most models of inflation do lead to a multiverse, and evidence for inflation will be pushing us in the direction of taking [the idea of a] multiverse seriously." While we can understand how the universe we see came to be, it's possible that the Big Bang was not the first inflationary period the universe experienced. Some scientists believe we live in a cosmos that goes through regular cycles of inflation and deflation, and that we just happen to be living in one of these phases.

Strange 'Methuselah' Star Looks Older Than the Universe The oldest known star appears to be older than the universe itself, but a new study is helping to clear up this seeming paradox. Previous research had estimated that the Milky Way galaxy's so-called "Methuselah star" is up to 16 billion years old. That's a problem, since most researchers agree that the Big Bang that created the universe occurred about 13.8 billion years ago. Now a team of astronomers has derived a new, less nonsensical age for the Methuselah star, incorporating information about its distance, brightness, composition and structure. "Put all of those ingredients together, and you get an age of 14.5 billion years, with a residual uncertainty that makes the star's age compatible with the age of the universe," study lead author Howard Bond, of Pennsylvania State University and the Space Telescope Science Institute in Baltimore, said in a statement. The uncertainty Bond refers to is plus or minus 800 million years, which means the star could actually be 13.7 billion years old — younger than the universe as it's currently understood, though just barely. A mysterious, fast-moving star Bond and his team used NASA's Hubble Space Telescope to study the Methuselah star, which is more formally known as HD 140283. Scientists have known about HD 140283 for more than 100 years, since it cruises across the sky at a relatively rapid clip. The star moves at about 800,000 mph (1.3 million km/h) and covers the width of the full moon in the sky every 1,500 years or so, researchers said. The star is just passing through the Earth's neck of the galactic woods and will eventually rocket back out to the Milky Way's halo, a population of ancient stars that surrounds the galaxy's familiar spiral disk. The Methuselah star, which is just now bloating into a red giant, was probably born in a dwarf galaxy that the nascent Milky Way gobbled up more than 12 billion years ago, researchers said. The star's long, looping orbit is likely a residue of that dramatic act of cannibalism. Distance makes the difference Hubble's measurements allowed the astronomers to refine the distance to HD 140283 using the principle of parallax, in which a change in an observers' position — in this case, Hubble's varying position in Earth orbit — translates into a shift in the apparent position of an object. They found that Methuselah lies 190.1 light-years away. With the star's distance known more precisely, the team was able to work out Methuselah's intrinsic brightness, a necessity for determining its age. The scientists also applied current theory to learn more about the Methuselah star's burn rate, composition and internal structure, which also shed light on its likely age. For example, HD 140283 has a relatively high oxygen-to-iron ratio, which brings the star's age down from some of the earlier predictions, researchers said. In the end, the astronomers estimated that HD 140283 was born 14.5 billion years ago, plus or minus 800 million years. Further observations could help bring the Methuselah star's age down even further, making it unequivocally younger than the universe, researchers said.