how to be wary of images on social networks

SPACE – This weekend we will have to roll our eyes, both literally and figuratively. As every year, the month of August offers ideal conditions for the Night of the Stars. An event whose popularity should double in view of the enthusiasm aroused by the James Webb space telescope, but which also echoes another news item of the week: the #Chorizogate, as it is now customary to call it.

Last week, renowned physicist Etienne Klein posted a photo of a slice of chorizo ​​on Twitter, implying that it was the star Proxima Centauri. A hoax for educational purposes to invite Internet users to beware. “ I’m sure if I hadn’t said it was a picture of James Webb it would have been a lot less successful “, he even confided to the HuffPost.

If the scientist explained and even apologized, the joke had the merit of underlining a major phenomenon: the sharing of false astro-images on social networks. ” It’s so extraordinary, you feel like you have access to another world and you want to believe it. But for all that, certain details must challenge us “, warns the astrophysicist and president of the French society of astronomy and astrophysics, Éric Lagadec, contacted by The HuffPost.

Dunes photo to another

Above all, we must remember that even when we speak of celestial objects millions of kilometers away, there is someone on Earth who took or who composed the image in question. “ There are many accounts that feature images with just ‘NASA’ in the credit. This is a first element that must raise eyebrows, NASA does not make an image alone “, explains Éric Lagadec. For example, on one of the recent images shared on its Instagram account, NASA indicates in credit “NASA, ESA, CSA, and STScI⁣⁣”.

As in any photographic object, we must not forget the post-production and retouching work either. This work is also directly carried out by scientists. The Hubble telescope did not take color shots. Then task the scientists and their computers to combine different takes of the same object, to pass the data and information through the mill, to ultimately give the impressive colors that we know. This colorimetric work carried out by scientists makes it possible to give meaning to what would otherwise be invisible to the human eye.

Finally, beware of the captions that often accompany images presented as unpublished on social networks. If there are many superlatives and few explanations, or even extremely precise figures, again, caution. An image that was relayed a lot on social networks last weekend presented itself as that of a “space vacuum” that one would have to cross for 732,536,988 years before being able to come across something.

“Obviously it is false, this number of years does not make any sense. We cannot have such precision., warns Eric Lagadec. In this case, the “space vacuum” in question was the molecular cloud of Barnard 68. An infrared filter shows that it is not at all empty.

Good accounts make good friends

In general, it must be remembered that an extraordinary discovery, an unprecedented scientific advance will never be made in a simple tweet, but will generate a press conference, scientific articles… “ With James Webb somewhere, science is done live. We are only beginning to write scientific articles which will then have to go through a peer review and verification process “recalls Éric Lagadec.

In this sense, to sharpen your critical eye, it is better to follow Twitter and Instagram accounts that have been certified or recognized for several years for their popularization work. NASA, the European space agency, the southern european observatorythe CNESor the Instagram account dedicated to the James Webb telescope.

Many recognized astrophotographers, professional or amateur, also regularly share content on social networks.

A little closer to the stars

Above all, if the launch of the James Webb space telescope still promises beautiful photos, it can’t do everything. ” James Webb is mainly intended for observing faint things, in near and mid-infrared, not for ultra-bright things like a star “says Eric Lagadec. It is, for example, its infrared capability that enabled the JWST to obtain such a precise image of these “cosmic cliffs”. By seeing in particular through gas and dust, it makes it possible to see barely formed stars.

Above all, the stars, even if they are hundreds or even thousands of times larger than our Sun, are located at distances far too great to offer precision. The closest star that offers the clearest vision of its surface is quite simply the Sun, recalls Éric Lagadec on Twitter.

The scientist indicates as an example that to obtain the picture below presenting the star Beltegeuse, 700 light years from us and with a radius a thousand times larger than the sun, it was necessary to use the largest telescope in the world, 40 meters long, located in Chile.

Sometimes astronomers combine the power of two telescopes, making it possible to obtain, as you can see below, a blurred image of the surface of Antares.

Returning to the photo of chorizo ​​shared by Étienne Klein, the scientist also recalls that this star in question is 50 times smaller than its cousins ​​presented above and above all that it is a red dwarf, whose surface images stars are very difficult to achieve. ” The stars for which you can almost get good images are red giants that are dying, they are very old stars. So be careful if you are presented with an image of the surface of a red dwarf, which is a star in the process of being born “, he adds. No offense to charcuterie lovers.

See also on The HuffPost: We’ve Never Seen Such a Black Hole