Test image from Gaia: Slightly shaky to start with, but it’ll get there. (Image: ESA/DPAC/Airbus DS)
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Largest ever space camera is ready to map a billion stars

The European Space Agency's Gaia telescope is so powerful, it see stars with power akin to measuring the width of a human hair at a distance of 500 km.

After its successful launch in December, the European Space Agency’s (ESA) Gaia has now taken up its position in space and is ready to survey the skies. With the help of two onboard telescopes focused onto the largest ever space camera, Gaia is estimated to catalogue nearly one billion stars in its 5-year mission.

Like Hipparcos before it, ESA’s Gaia will map stars in the Milky Way. It will do this by measuring the brightest billion objects and determine their three-dimensional distribution and velocities. It also has the ability to measure the temperature, mass, and chemical composition of these billion objects.

Gaia will be able to discern objects up to 400,000 times dimmer than those visible to the naked eye. The positional accuracy of its measurements are akin to measuring the width of a human hair at a distance of 500 km.

The process will involve scanning each part of the sky an average of 70 times over its five-year mission lifetime, which means scanning the entire sky twice every 63 days, once through each of the two telescopes, making it a powerful tool for spotting time-evolving phenomena such as binary systems, supernovae, and exoplanets. Compared to Hipparcos, Gaia will be able to measure 500 times the number of stars, extending to objects 1000 times dimmer than the dimmest that Hipparcos could catalogue.

The technology that makes this possible is the largest camera ever launched into space – 940 million pixels. That is why a lot of effort before launch was on figuring out exactly how to get the huge amount of data Gaia will produce back down to Earth.

When a picture is taken a number of charged-coupled devices (CCDs) – the stuff most digital camera sensors are made off – are dedicated to spotting objects before they fall onto the main focal plane. This allows the instrument to track the objects as they pass and only retain small regions around the object, reducing the file-size needed to be sent to Earth. In five years it will send only 100 TB of data. Once the data arrives to Earth, there is a system in place to analyse the data and distribute alerts to ground-based observatories if anything quickly evolving and potentially interesting is spotted, such as supernovae.

The catalogue produced by Gaia is expected to contribute to many areas of astrophysics, multiply our database of exotic objects such as exoplanets, white and brown dwarfs, and supernovae many-fold, contribute to more precise measurements of General Relativity, help to constrain the measurements of the presence and location of dark matter, and give us more accurate information about our galactic neighbourhood and its evolution.

Gaia was successfully launched on 19 December. After a month’s transit, it is now in orbit at about 1.5 million km away from Earth. By virtue of its position opposite the Sun from the Earth and its large sunshield, it will be able to see objects as close as 45 degrees from the Sun, allowing it to spot asteroids with orbits that lie between the Earth and the Sun, which are candidates for Earth collision, and very difficult to observe from the ground.

Staff on the ground are conducting in-orbit testing, during which the exact orbital parameters are determined, and all systems are tested for performance. Calibration images have been obtained, and the ground team is working on procedures to resolve a few remaining issues, such as reducing contamination on the CCDs and dealing with sunlight diffracted around the sun-shield.

Beyond the alert system allowing quick ground-based follow up, the first proper Gaia catalogue will take two years to complete and will be made available to the wider scientific community. Following this, new iterations will be issued about once a year, which will add more precisely determined characteristics of these objects. It is expected that Gaia’s database will have many new discoveries waiting to be mined from it, fuelling astronomers for decades to come.

Ben Dryer has received funding from the UK Space Agency to perform Gaia data analysis.

This article was originally published on The Conversation. Read the original article.The Conversation

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Why are online jokes funnier without punctuation and capital letters?

Academics and social media users weigh in on Twitter’s most unexplained phenomenon. 

The first person to notice it did so in 2010. “Sometimes I think a twitter joke is funnier if you omit punctuation,” tweeted @zacharylittle on 2 April. He was a pioneer. It took two years for anyone else to express the same thought, but they did so in droves. “I like not using punctuation like commas on twitter because its somehow funnier lol,” said @chxrliesheen, sans apostrophe. “I never use punctuation on twitter and tumblr I just think its funnier ok,” exclaimed @julieamarch. From then until now, people have been constantly questioning the phenomenon, but there are still no answers.

Why exactly are Twitter jokes funnier when they have grammatical errors, discard punctuation, lack capital letters, or are misspelled?

“There is a frisson, or sense of pleasure, from playfulness in language,” Dr Deborah Tannen, a professor of linguistics at Georgetown University, tells me over email – in which she demonstrates some of this playfulness herself. “writing wihtout caps, proper punctation, and leaving misspellings uncorrected also feels like private communication, like whispered kjokes, and therefore has the same potential thrill.”

Dr Hugh Rabagliati, a Chancellor's Fellow at the School of Philosophy, Psychology, and Language Sciences at the University of Edinburgh, warns me that most of his knowledge on the subject comes from “spending too much time on Twitter, rather than any obvious academic work”. It is true that research into the area is lacking – books about “internet language” get outdated quickly, and seem to focus on email and chatrooms, rather than more modern social media. “The misspellings [on Twitter] are often beautifully calibrated, like a very subtle malapropism, and the grammar errors are designed to make familiar material feel out of kilter,” he says.

Sometimes humour is found when grandiose sentiments are contrasted with train-wreck grammar, he argues, whereas other times the language can be exclusionary and people share it to prove they “get” the joke.

Perhaps the most famous Twitter user who has mastered the technique of the misspelled tweet is Jonathan Sun. Sun has gained 168,000 followers posing as an “aliebn confuesed abot humamn lamgauge”, and is part of what is known as “weird Twitter”, a subset of the site where humour is surreal and often bolstered by misspellings, a lack of punctuation, and grammatical errors. But while “weird Twitter” takes it to the extreme, many other arguably “normal” Twitter users will uncap the start of their Tweets or the word “I”.

“i’m not really sure why but i’ve been going out of my way to un-cap for ages,” one anonymous Twitter user told me via a direct message on the site. “i recognise that it is a stupid waste of time, ive had partners mock me for it.” Possibly, they theorise, they do this because they used to edit copy as part of their job. “it could be a reaction to that, to be completely armchair psychology about it.”

Naomi Baron, a professor of linguistics at American University and author of Words Onscreen: The Fate of Reading in a Digital World reinforces this point. She argues that language users are always looking for ways to distinguish their voices and express emotion. “A bevy of authors – from the poet e.e. cummings to social media scholar danah boyd – have further personalised their identity by eschewing the normal capitalisations in their names,” she says. “When it comes to social networking sites such as Twitter, lack of capital letters lends a tone of informality that makes the messages feel more speech-like.”

It’s hard to admit that you’re deliberately making mistakes in order to look offhand, as you are essentially revealing you try-very-hard-to-look-like-you’re-not-trying-at-all. But Rebecca Reid, a 25-year-old journalist, admits this is why she used to uncap her tweets. “Honestly I literally thought it made me look cooler,” she says. “I saw my sister doing it, and she's a couple of years younger and very trendy, so I thought it was just what we were doing. So I copied her. This is so tragic from me. And after a while I realised that it wasn't making me seem edgy, it was making it seem like the shift button on my key board was broken.”

It is true that informality is important in written messages, as a 2015 study revealed that ending text messages with a full stop was perceived to be insincere, most likely because it is seen as a sign of aggression. Twitter jokes that are written similarly formally – with full stops and capital letters – might also seem insincere, or be less inviting or inclusive than those with deliberate mistakes, run-on sentences, or five-too-many exclamation marks.

“There's also a phenomenon that linguists have only started discussing in the last decade, called ‘Eggcorns’,” says Rabagliati. “Here the speaker has learned a misanalysed locution. The phenomenon is named from the case of a woman who had, all her life, misheard the word acorn as ‘eggcorn’. ‘To all intensive purposes’ is a similar error. These mistakes play on our fear that our knowledge of language might not be as robust as we want to believe – think about all those words that you've read, but never heard aloud. Plus, the errors are fun because they demand some backwards reasoning to reconstruct.” 

More academic research is needed for a final answer on the phenomenon, but one thing is certain. If uncapitalising things on Twitter is cool, writing an 800-word article about it certainly isn't. 

Amelia Tait is a technology and digital culture writer at the New Statesman.