A collection of the key observational evidence that supports the Big Bang model of the universe’s origin and evolution.
In the late 1990s, two independent teams used Type Ia supernovae as standard candles to trace the universe’s expansion history. Their surprising conclusion—that cosmic expansion is accelerating—revolutionized cosmology and led to the concept of dark energy, a mysterious force driving the universe apart.
Primordial helium, forged in the first minutes after the Big Bang, provides a crucial test of the hot Big Bang model. Its measured abundance matches theoretical predictions, reinforcing our understanding of the universe’s origin and evolution.
The cosmic microwave background (CMB) is the oldest light in the universe, a relic of the hot Big Bang. This article explains how astronomers measure it from Earth, what it reveals about cosmic history, and why it anchors our modern understanding of the cosmos.
The Hubble–Lemaître law describes the expansion of the universe, showing that galaxies recede at speeds proportional to their distance. It is a cornerstone of modern cosmology, linking the Big Bang to the cosmic microwave background and the large-scale structure of the cosmos.
The universe is 13.8 billion years old. This definitive guide explains how astronomers measure the age of the cosmos using the cosmic microwave background, stellar evolution, and the expansion rate, and traces the universe’s evolution from the Planck epoch to the present day.
Acoustic peaks are periodic ripples in the cosmic microwave background temperature, imprinted by sound waves in the early universe. These peaks encode the fundamental physics of the Big Bang and have become a cornerstone of modern cosmology, revealing the composition and evolution of the cosmos.
Explore the compelling evidence for the Big Bang theory, from the expanding universe and cosmic microwave background to the formation of the first elements. Learn how astronomers have pieced together the story of our cosmos.
Redshift is the stretching of light from distant galaxies, revealing the expansion of the universe and the history of cosmic evolution from the Big Bang to the present day. This interactive guide explores the epochs, evidence, and missions that define our understanding of the cosmos.
The Planck space telescope mapped the cosmic microwave background with unprecedented precision, revealing the universe’s age, composition, and evolution. Its observations refined the standard cosmological model, measured key parameters like the Hubble constant, and provided a detailed picture of the early universe from the Planck epoch to the present day.
The cosmic microwave background is uniform to one part in 100,000, a puzzle solved by cosmic inflation. This article explains the CMB’s origin, the epochs of the early universe, and how missions like COBE, WMAP, and Planck have measured it.
