European space telescope Euclid spots oldest quasars yet
Think of quasars as time machines. Rare but revealing. They are light from the beginnings of the universe that let astronomers investigate how early galaxies
Think of quasars as time machines. Rare but revealing. They are light from the beginnings of the universe that let astronomers investigate how early galaxies formed. Quasars emit primordial light. They are far, far away, both in terms of time and distance. They are easy to confuse with other celestial sources of light, like stars that are closer to Earth. But when we do detect them, they tell astronomers a lot about the earliest moments of the universe, and that knowledge helps us learn more about our place in it. The European Space Agency's Euclid space-based telescope launched in 2024 to map the universe. ESA has now released images of two of the most ancient quasars ever located. They are just two out of a crop of 31 quasars that hark back to a time when the universe was a mere 670 million years old. That's within the first 5% of its current age.
"Before, we could only find a handful of the very brightest ancient quasars, but Euclid lets us search far more efficiently across huge areas of [the night sky] to capture much fainter light. It's a unique tool for quasar hunting," says Daming Yang, the lead author of a study about the new findings, published July 6, 2026. Hunting for quasars: An archaeological dig of the universe The two oldest quasars in the new discovery are known as EUCL J172902.75+641018.1 EUCL J125308.55+705432.3 Several of the new quasars discovered by Euclid have a redshift of 7 or above, indicating they are farther away, hence further back in time Image: ESA/Euclid/Euclid Consortium/NASA, image processing by the Euclid Science Ground Segment and Antoine Basset (CNES) If you look at the image below, you will find decimal numbers next to the quasar names. These numbers refer to their respective redshifts. The redshift is a measurement of a light source's distance and motion in the cosmos in relation to Earth.
Redshift is sometimes compared to the Doppler Effect in sound — the idea that when you move towards or away from a sound, such as an ambulance siren. When it's moving toward you, you hear it at a higher pitch or frequency, and as you move away from it, you hear the same sound at a lower pitch or frequency. Higher and lower pitches are the same as bass sounds and treble sounds in music. The difference is that redshift relates to light rather than sound. Think back to these new quasars from the earliest moments of the universe — they are far from us. Their wavelengths are longer, shifted into the red zone of the spectrum. Hence, redshifted. Our galaxy, the Milky Way. You can see the two most ancient quasars marked in red in the top left-hand corner. The yellow dots show the location of the other 29 new quasars.
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