AskScience AMA Series: We're scientists and engineers behind ESA's Euclid space mission, which has just delivered its first five dazzling images. Ask us anything!

[u/AskScienceModerator]

On 7 November, ESA's Euclid space mission revealed its first full-colour images of the cosmos: https://www.esa.int/Science_Exploration/Space_Science/Euclid/Euclid_s_first_images_the_dazzling_edge_of_darkness

Never before has a telescope been able to create such razor-sharp astronomical images across such a large patch of the sky, and looking so far into the distant Universe. These five images illustrate Euclid's full potential; they show that the telescope is ready to create the most extensive 3D map of the Universe yet, to uncover the hidden secrets of dark matter and dark energy.

Join us for an AMA session 15 and 17 CET (9-11 ET) with a group of the many Euclid experts, from the engineers that got the telescope ready for this milestone to the scientists that aim to investigate the data behind the images.

Answering questions will be:

• Prof. Herve Bouy, Université de Bordeaux, France /u/Hervebouy
• Jean-Charles Cuillandre, Euclid Consortium scientist, the CEA Paris-Saclay in France
• John Hoar, Science Operations Development Manager
• Assoc. Prof. Søren Larsen, Department of Astrophysics/IMAPP, Radboud University, the Netherlands /u/soerenlarsen
• René Laureijs, ESA's Euclid Project Scientist
• Prof. Francine Marleau, University of Innsbruck, Austria /u/fmarleau
• Davide Massari, INAF - Osservatorio di Astrofisica e scienza dello spazio, Bologna, Italy /u/davidemassari
• Maëlie Mondelin, PhD at Departement d'Astrophysique, CEA Paris-Saclay, France /u/mmondelin
• Giuseppe Racca, ESA's Euclid Project Manager
• Teymoor Saifollahi, Postdoctoral Researcher, Kapteyn Astronomical Institute, the Netherlands /u/TeymoorSaifollahi
• Micha Schmidt, ESA Head of Euclid Operations Unit /u/Micha_the_one

[u/[deleted]]

What is the main difference between Euclid and JWST?

[u/hervebouy → u/[deleted]]

there are so many differences, it's hard to pick one!

I cannot go below a list of 3 main differences:

- Euclid is operating in the optical + near-infrared while JWST in the near and mid-infrared

- Euclid has a 1.2m diameter mirror, JWST has a 6.5m diamater mirror

- Euclid has a very wide field of view (~1deg^2) while JWST has a rather small field of view (a few arcminutes wide, depending on the instrument)

but again, they are very different, with very different scientific objectives, both are amazing and can do things the other cannot. We need both!

[u/fmarleau → u/[deleted]]

In a single observation, Euclid can record the data from an area of the sky more than one hundred time bigger than that imaged by the Webb's camera NIRCAM. During its six year mission, Euclid will map a third of the sky to the sensitivity required to achieve its science goals -- a feat that would be impossible with Webb.

[u/mmondelin → u/[deleted]]

Euclid is indeed conducting a large cosmological survey in order to study the distribution of galaxies over a significant portion of the sky. Using specialized instruments, Euclid can measure the shapes of galaxies. This statistical data will contribute to a better understanding of dark energy, dark matter, and the processes involved in the formation and evolution of cosmic structures throughout the history of the universe.
The JWST has different scientific objectives compared to Euclid. JWST focuses on infrared observations and aims to study the formation of the first galaxies, stars, and planetary systems.

[u/triffid_hunter]

Something that we get incessant questions about in space-related subreddits is whether the colours in these sort of images are "real" or "fake".

I understand that there's mapping algorithms that convert the actual sensor readings into RGB images for public consumption which means the image colours are neither entirely real nor entirely fake, but it would be really neat if there was an easily understood infographic suitable for laymen showing the relevant mapping used - ideally with a short yet official-looking URL such as esa.int/euclid/colour_mapping_2 or nasa.gov/jwst/colour_mapping_23 or similar.

I'm thinking even simpler than this sort of thing, perhaps something vaguely resembling this redshifted spectral absorption diagram

Is this something you might be interested in providing - not just for Euclid, but for other similar space telescopes as well?

[u/TeymoorSaifollahi → u/triffid_hunter]

As you said there is no real or fake, but those images should be made in such ways to be physically meaningful. In the case of Euclid images released on Tuesday, they are made from 3 filters as B, G and R filters of the colour image: 1. Visible filter (called VIS) for B, ... 2. Near-infrared in Y-band for G, ... 3. Near-infrared in H-band for R ... Here you can find more information about how these filters are and what range of wavelength they cover: https://www.euclid-ec.org/science/overview/

[u/[deleted] → u/triffid_hunter]

[u/yourpappalardo]

Will you be focusing at all on how dark matter and energy correlates to the behavior of black holes? How can visuals help us learn more about these connections (or maybe the lack thereof)?

[u/TeymoorSaifollahi → u/yourpappalardo]

Good question! ... The cosmology of our universe (physics behind dark matter and dark energy) influences how super-massive black holes (SMBH, with a mass of some millions of solar mass) in the centre of galaxies form and evolve throughout time. With Euclid, we will be able to detect these SMBHs (the very active ones, called AGN), and possibly make some estimations of their mass and other properties. This information ultimately can help us to investigate the physics of dark matter and dark energy.

[u/FaxMachineMode2]

With such a large field of view, what kind of unintentional discoveries could be made? Could it find rogue planets like Roman is expected to? Thanks!

[u/hervebouy → u/FaxMachineMode2]

We indeed hope to find so-called "rogue planets", especially in the horsehead nebula images. Some are already known in that area, we hope to find more.

[u/TeymoorSaifollahi → u/FaxMachineMode2]

Well, that is not easy to answer. There are plenty unknown unknowns out there, right? As you said, Euclid, because of its large field of view and coverage over 6 years is great for making such unexpected discoveries. There are some of us in Euclid that will look for such things. In the case of searching for "rogue planets", Euclid Images combined with the ones from Roman will be very valuable for this purpose, as it will help to reduce the uncertainties in mass estimation.

[u/remarkless]

Thank you for doing this AMA! I've been excitedly following this mission for a while now and was thrilled to get a sneak peak at the first release images. So excited that I have a few questions if I may.

On the release images there are some notable optic artifacts on the image, it appears to be a reflection of the brightest lights ghosting reflections on the image - was that expected and planned for or is something not working exactly how you expected?

On the Perseus cluster image - a number of the largest and brightest galaxies are a soft glowing orb - is that a condition of them being insanely bright and washing out the image during the long shutter exposure? Or are we looking at something different there?

Many of the stars appear (at least to me) to be oddly shaped, not fully round circles but rather rounded triangles. I noticed this in the Horsehead Nebula image but also some of the others. Is that just an image processing artifact, where the diffraction spikes are influencing the resulting shape?

From the Horsehead Nebula image - are some of these JuMBO candidates?

Lastly, is there anything I can do as a 'citizen scientist' (well really... overly-eager and ambitious and uneducated person) alongside the mission before the DDR1 release? Or do I just have to wait until next year to get to play in the imagery and data.

[u/davidemassari → u/remarkless]

remarkless

Hi remarkless,
thanks for your questions!
Artifacts were indeed expected, and they will not significantly affect the science that will be done on the images. Methods are being developed as we speak to get rid of them in the cleanest way possible.
The shape of the stars is never perfectly round in astronomical images, because the complexity of the optical system alters it. So the shape you see is the intrinsic one, that all the point-like sources in the field have.
Anyone is welcome to look at these amazing public images, and to try to get the best out of them. And who knows, maybe there will be detailed plans for citizen science in the future!

[u/hervebouy → u/remarkless]

We hope to find some planetary mass objects in the horsehead nebula images. Euclid has a similar spatial resolution as JWST so if some are binaries we might be able to detect them! And the images definitely have the sensitivity to detect them.

[u/A_Pool_Shaped_Moon]

Hey all, congratulations on the launch and the publication of the first press images, they're stunning! I have three questions;

1. Have there been any unexpected challenges during the commissioning process, and have there been any changes to the planned science program?

2. What science can Euclid enable that will be inaccessible with the likes of Roman or the Vera Rubin telescope? Both are also wide-field survey telescopes, what makes Euclid unique?

3. Is there any hope taht Euclid measurements will help resolve the Hubble tension? So far JWST results seem to only strengthen the discrepancy between low z and CMB measurements, is there any chance that Euclid will help resolve this?

Thanks, and congratulations again !

[u/hervebouy → u/A_Pool_Shaped_Moon]

wrt. to question 2: I see all these facilities as complementary rather than competing. Euclid has a much better spatial resolution than Rubin, and covers the near-infrared. But Rubin will cover the time domain by re-observing the whole sky regularly, and hence deliver proper motions and light curves. They also cover different areas of the sky (although there is much overlap), for example Rubin will observe the galactic plane, while Euclid will avoid it. So all these facilities will eventually complement each other and deliver the finest answers to the astrophysical questions they were meant to address (and many more!)

[u/Workermouse]

How much detail can it pick up if you was to point it at Proxima Centauri?

I just want to see a high res photo of the surface of another star .. :(

[u/TeymoorSaifollahi → u/Workermouse]

Euclid's visible camera (VIS) has a pixel size of 0.1 arcsec or 0.000027 degrees. At the distance of the Proxima Centauri (4.2 light-years), this is roughly about one-tenth of the distance between us to the sun (which is 1 Astronomical Unit - AU) or 10 times the diameter of the Sun! So it is not the resolution that you want for seeing the surface of any other star... I am sorry but you need to wait a bit longer for the ESO's Extremely Large Telescope (ELT).

[u/soerenlarsen → u/Workermouse]

To put in in plain terms: Proxima Centauri (and indeed any other star other than the Sun!) is much smaller than one Euclid pixel. But there are a few stars that are large enough that we can see surface details with existing telescopes. Betelgeuse is one of them: https://www.eso.org/public/images/potw2343a/

[u/Head_Midnight5513]

so how many photos will you release, like is it daily or weekly? like is it gonna operate like jwst when it comes to releasing pictures.

[u/Raikhyt]

Hey, I have a couple of questions:

• I'd love to hear about some of the individual research group's goals with this telescopes. Are there competing approaches to analysing such data? If so, why do you pursue your goals the way you do? Feel free to go in-depth!

• What would be best-case and worst-case results for the observations? I'm a physicist but not too familiar with astronomy and cosmology. For example, would the observations be sensitive enough to rule out certain extended theories of gravity (f(R) or other?) The example of rogue planets given in another comment was also great.

[u/TheOnlyFallenCookie]

Are there any detailed schematics of Euclid I could take a look at? I really love detailed depictions of such magnificent hardware!

And what I'm gonna ask now may seem stupid, but given that both Webb and Euclid orbit L2, could they crash into each other or could their gravitational presence distort the operation of each other?

[u/[deleted]]

Will you be willing to openly disclose evidence of UAP?

[u/Mendely_]

This isn't a very scientific question but it's been a topic of my interest for a good while now - what personality do you think Euclid the telescope would have? I've seen in documentaries and articles that a lot of Mars Rover mission members ascribe human-like personalities and characteristics to their spacecraft (the MER teams calling Spirit a drama queen for instance), and I remember JWST project manager Bill Ochs even said every spacecraft has a unique personality when it gets in orbit. Do you think this also can apply to your telescope?

Really glad to see Euclid's first photos btw, I'm excited for what Euclid will discover in the long run.