This interactive 3D visualization shows about 30,000 galaxies observed by the Dark Energy Spectroscopic Instrument (DESI) in about 5 hours. DESI targets four types of galaxies that you can toggle on/off below:

• BGS: nearby bright galaxies,
• LRG: luminous red galaxies,
• ELG: emission-line galaxies, and
• QSO: galaxies containing a supermassive black hole, known as quasars.

You can also see thin lines (LYA) in front of the most distant quasars, showing where they backlight the tenuous inter-galactic medium to map its contents.

The volume of space shown here is very long and thin, and would fit behind your palm held at arm's length. Use the slider below to select your distance from earth, or click PLAY. When the animation is paused, use your mouse or finger to look around at the nearby galaxies.

Cosmic distance can be measured several ways which are displayed below:

• Redshift measures the stretching of observed wavelengths due to cosmic expansion,
• Comoving distance in Gpc (1 Gigaparsec equals 3.26 billion light years) measures distance in the present universe, and
• Lookback time Gyrs (1 Gigayear equals 1 billion years) measures how long the light we observe today has been traveling.

Our direct measurements of galaxies provide angles and redshifts, but we need to assume a model of the cosmic expansion history to convert these to 3D positions in the universe today. The main parameters govering the recent expansion are the amounts of matter and dark energy present in the universe today.

Vary the sliders below to change the assumed expansion history and observe the effects on the 3D galaxy positions and the age of the universe. Note that when the two numbers do not add up to exactly one, the resulting universe is curved, and the familiar rules of Euclidean geometry no longer apply (for example, the angles of a large triangle no longer sum to 180 degrees).

This visualization was developed by David Kirkby using proprietary DESI data.