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The universe is young.So is our understanding of it.

Landmark papers, today's discoveries and the far future of the cosmos, explained plainly and always linked to the source.

Explore the researchJourney through deep time

Latest discoveries, sourced.

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Updated Oct 13
  1. The Invisible Architecture Between the StarsAAS Nova
  2. Gelato: A Mission Concept for Comet Surface Sample ReturnAAS Nova
  3. NASA Demonstrates Next-Generation Heat Shield TechnologiesNASA
  4. A Pulsar in a Rare Triple SystemAAS Nova
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The papers that built modern astronomy.

Each one changed what we know. Read our plain-English summary, then the original. Read them in order.

1912

Leavitt and Pickering, Harvard College Observatory Circular

Henrietta Leavitt's Law: The Key to Cosmic Distances

Found in 1912 that brighter Cepheid stars pulse more slowly. Henrietta Leavitt's law became the first standard candle for measuring cosmic distances.

Stars

1916

Schwarzschild, Sitzungsberichte der Königlich Preussischen Akademie der Wissenschaften zu Berlin

Schwarzschild's Solution: The Birth of the Black Hole

Found in 1916 the first exact solution of Einstein's equations, with the radius now known as a black hole's horizon. Karl Schwarzschild's paper, explained.

Black holes

1925

Payne, Harvard Observatory Monographs No. 1 (PhD thesis, Radcliffe College)

Cecilia Payne's Thesis: Stars Are Made of Hydrogen

Showed in 1925 that stars are mostly hydrogen and helium. Cecilia Payne's PhD thesis decoded stellar spectra and revealed what the universe is made of.

Stars

1992

Smoot et al., The Astrophysical Journal

COBE's Cosmic Ripples: The Seeds of Every Galaxy

Detected in 1992 the first ripples in the cosmic microwave background, about 30 millionths of a degree. George Smoot's COBE result and why it won a Nobel.

Cosmology

2016

LIGO Scientific Collaboration and Virgo Collaboration, Physical Review Letters

First Gravitational Wave Detection: LIGO's GW150914 Paper

Detected gravitational waves for the first time, from two black holes merging 1.3 billion light-years away. The 2016 LIGO-Virgo GW150914 paper.

Gravitational waves

2017

LIGO Scientific Collaboration and Virgo Collaboration, Physical Review Letters

GW170817: The Neutron Star Merger Seen in Waves and Light

Detected in 2017 two neutron stars merging 40 megaparsecs away, also seen as a gamma-ray burst and a kilonova. The LIGO-Virgo GW170817 discovery paper.

Gravitational waves

2019

Event Horizon Telescope Collaboration, The Astrophysical Journal Letters

First Image of a Black Hole: The M87* Shadow Explained

Captured in 2019 the first image of a black hole: a ring of light around the shadow of M87*, 6.5 billion Suns. The Event Horizon Telescope's paper.

Black holes

Browse all 104 papers

Deep time

Squeeze the age of stars into one human life, and the universe is 5 days old.

Stars will keep forming for about 1014 years. Measured against that, our 13.8 billion years is a newborn's first week. Beyond the stars, the timeline runs past 10100 years.

You are here
A logarithmic timeline from the Planck time to beyond 10 to the 100 years, divided into the Primordial, Stelliferous, Degenerate, Black Hole and Dark eras. Today, 13.8 billion years after the Big Bang, falls early in the Stelliferous Era.
All five eras, from 10−43 seconds to 10100 years

Where research is moving.

24,111

astrophysics papers posted to arXiv in the last twelve months.

Fastest growing: Instruments and methods, +30.9% on the previous year.

Open Research Pulse
  1. Instruments and methodsastro-ph.IM
    4,396+30.9% vs prior year
  2. Planets and exoplanetsastro-ph.EP
    3,432+14.1% vs prior year
  3. Cosmologyastro-ph.CO
    5,506+11.8% vs prior year
  4. Stars and the Sunastro-ph.SR
    5,247+10.5% vs prior year
  5. Galaxiesastro-ph.GA
    7,535+10.3% vs prior year
  6. High-energy astrophysicsastro-ph.HE
    6,506+10.0% vs prior year

Start with a question.

The Pillars of Creation in the Eagle Nebula seen by Webb in near-infrared light: towering columns of gas dotted with newborn stars.

Stars

The birth, life and death of stars, the engines of the Stelliferous Era.

The first image of a black hole: a glowing orange ring of hot gas around the dark shadow of M87*.

Black holes

Regions where gravity wins completely, from stellar remnants to galactic giants.

The Cartwheel Galaxy imaged by Webb: a bright core and a pink, spoked outer ring left by a galactic collision.

Galaxies

How galaxies form, collide, grow and die.

The Hubble Ultra Deep Field: thousands of galaxies of every shape and color in a tiny patch of dark sky.

Cosmology

The origin, shape and expansion of the universe as a whole.

The Cosmic Cliffs in the Carina Nebula imaged by the James Webb Space Telescope: a glowing ridge of gas and dust under a star-filled blue sky.

Telescopes and missions

The instruments that turn photons into knowledge.

Watch it explained.

Hand-picked videos from scientists and the best explainers, each with our short summary.

TIMELAPSE OF THE FUTURE: A Journey to the End of Time (4K)

A cinematic timelapse of the future of the universe, jumping forward in ever larger steps from the present to the death of the Sun, the end of all stars and beyond. Pure visuals and music, no prior knowledge needed. melodysheep

The video library
Earth setting behind the cratered far side of the Moon, photographed by the Artemis II crew from the Orion spacecraft.

Newsletter

This week in papers.

Five new results in one line each, plus one landmark from the archive. One short email a week, no ads.

New here? Start with the 27 papers that built modern astronomy