First light (8/3/23)

Good afternoon, and happy Thursday. It’s a wonderful day to dive into some space science, so let’s get into it.

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Euclid’s First Light

A million miles away from Earth, balancing on a point in space where the gravitational pull of the Earth and Sun even out, a new telescope just switched on its instruments and began its hunt for the most abundant and elusive stuff in our universe: dark energy.

“The outstanding first images obtained using Euclid’s visible and near-infrared instruments open a new era to observational cosmology and statistical astronomy,” Yannick Mellier, Euclid Consortium lead, said in a release. “They mark the beginning of the quest for the very nature of dark energy, to be undertaken by the Euclid Consortium.”

The dark side: 95% of the universe is made up of stuff we can’t see or detect. We only know it’s even there because of the effects we see it exert on the universe—specifically, that the universe is expanding at an accelerating rate.

There are signs of dark matter and energy on smaller scales, too. It seems like there should be something extra beyond what we can see holding galaxies together and maintaining their shapes, and scientists have observed stars and clouds of gas in interstellar space behaving as though unseen gravitational forces are moving them around. But they don’t know how or where those forces are coming from.

That’s where Euclid comes in.

ESA’s newest space telescope is designed to observe a huge quantity of galaxies up to ~10B light-years away in three dimensions (that is, using time as a parameter). The data Euclid collects is meant to help researchers hunting for dark matter and energy uncover new signs of their effect on the cosmos.

New neighbor: Euclid arrived at Lagrange Point 2 (or L2) on July 28. L2 is exactly on the opposite side of the Earth from the Sun, about a million miles away from us, and it’s situated so that the gravitational forces of the Earth and Sun along with its own orbital motion keep spacecraft suspended there without having to do a whole lot of station-keeping. That makes it a prime vantage point for observing the universe.

Euclid isn’t the first craft there, and if L2 sounds familiar, it’s probably because JWST lives there too. Though the two powerful space telescopes now share an address, they’ve got significantly different missions to accomplish.

• JWST is designed to probe the deep universe just about as far away and as far back in time as you can get. To do this, it’s probing the near- and mid-infrared, since light that old has been stretched out and redshifted as it’s traveled across the vast void of space.

• Euclid, on the other hand, is designed to image tons and tons of galaxies and is most interested in their structure, as well as the light they emit on the visible spectrum and near-infrared.

Coming online: Euclid is equipped with two instruments to help it on its mission:

1. VIS, or the VISible instrument, which will take hi-def photos of distant galaxies so researchers can analyze their shapes and structures. The VIS commissioning image is above in black and white.

2. NISP, or the Near-Infrared Spectrometer and Photometer, which will image galaxies in infrared as well as measure the distribution of light waves coming from them. The NISP images are helpfully filtered in red.

NISP has a “grism” mode, which stretches the wavelengths coming from individual stars within a galaxy into vertical bars. The image below displays the functioning grism mode on the instrument.

Looking forward: Euclid’s nominal mission is six years long. Right now, it’s in the process of commissioning, and over the next few months researchers back home will continue to collect calibration data and fine-tune the instruments to get it ready for business. That’s when the real dark energy and matter-hunting begins.

Other News from the Cosmos

• A neutron star emitting very fast radio bursts from within our own galaxy, observed for the first time in 2020, illuminates the mysterious properties of more distant instances.

• Aeolus, an ESA wind observation satellite, reentered the atmosphere via a new method for responsible removal (via Payload).

• A machine learning model designed to detect cloud cover in satellite images was trained in orbit.

• Dunes on Earth and other planets signal environmental and geological changes to researchers.

• Earth’s oldest craters from distant asteroid impacts are disappearing.

• Magnetic fields may appear spontaneously in turbulent plasma, according to a Columbia University study.

• An algorithm to identify potentially hazardous asteroids has found its first suspect.

The View from Space

About two weeks ago, a small telescope in Arizona caught this massive plume of gas erupting from the surface of the Sun. Our hometown star has been extra active lately, as we approach a solar maximum in 2025.