# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DXPGJZVAPiE
- **Gondola URL:** https://gondola.cc/posts/64172346-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/e93b711bad.jpg
- **Posted:** 2026-04-17T14:21:41.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

BREAKING in cosmology: the Dark Energy Spectroscopic Instrument (DESI) has completed its primary five-year survey, delivering the most detailed 3D map of the Universe ever constructed.

Mounted on the NSF Nicholas U. Mayall 4-meter Telescope at Kitt Peak, DESI uses multi-object spectroscopy to measure the redshifts of tens of millions of galaxies and quasars. Each observation captures spectra from up to 5,000 objects simultaneously via robotically positioned optical fibers, enabling an unprecedented data collection rate.

So what does “3D map” actually mean here?
Astronomers combine two key measurements:

* Angular position on the sky (2D)
* Redshift (z), which encodes distance via cosmic expansion

This converts sky coordinates into a full 3D distribution of matter across billions of light-years.

Key scale:
DESI mapped more than 47 million galaxies and quasars, tracing structure over roughly 11 billion years of cosmic history. That means we are not just seeing where galaxies are, but how structure evolved over time.

Why this matters for dark energy:
Dark energy is the dominant component of the Universe’s energy density, driving accelerated expansion. DESI constrains it using baryon acoustic oscillations (BAO), subtle imprints from early-universe sound waves that act as a “standard ruler.”

By measuring how the BAO scale appears at different redshifts, researchers can reconstruct the expansion history of the Universe with high precision. This directly tests whether dark energy behaves like a cosmological constant or evolves over time.

#space #cosmology #darkenergy #astrophysics #astronomy

## Stats

- **Views:** 2,357
- **Likes:** 172
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- **Comments:** 1

## Tags

space, cosmology, darkenergy, astrophysics, astronomy

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