ned.ipac.caltech.edu
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NASA/IPAC Extragalactic Database (NED) is a centralized, cross-referenced database of extragalactic objects, serving as a go-to resource for galaxies and cosmology. It provides summarized and downloadable data—positions, redshifts, multi-wavelength photometry, spectra, images, and bibliographic references—plus search and visualization tools to explore and compare objects across surveys.
More resources on Galaxies & Cosmology
Lambda Archive
NASA's Legacy Archive for Microwave Background Data Analysis hosts the released maps, power spectra, likelihood codes, and simulation tools from COBE, WMAP, Planck, and ground-based CMB experiments, so you can work with the actual cosmological datasets rather than summaries.
The Early Universe (MIT 8.286)
Modern cosmology, beginning with classical expanding-universe models and moving to the particle physics of the hot early universe and cosmic inflation. Includes 23 lecture videos by the originator of inflationary cosmology, slide notes, problem sets, and exams with solutions.
Introduction to Cosmology
An undergraduate textbook deriving the Friedmann equations, then applying them to the expansion history, nucleosynthesis, recombination, the microwave background, and structure formation. Requires calculus and basic physics; leaves you able to compute distances and ages for a given cosmological model.
Galaxies in the Universe
An upper-undergraduate survey of the Milky Way, stellar populations, spiral and elliptical systems, galaxy dynamics, groups and clusters, and galaxy evolution. Problem sets emphasize order-of-magnitude estimates, so you learn to reason quantitatively about observed galaxy properties.
Cosmology
A graduate-level treatment that derives the expansion history, cosmological perturbation theory, microwave background anisotropies, and inflation from general relativity, with the algebra shown rather than quoted. Assumes fluency in tensor calculus and field theory before the first chapter.
ESA Planck Mission
Official European Space Agency site for the Planck space telescope, which mapped the cosmic microwave background. It explains the mission and instruments and links to all-sky maps, data releases and papers, helping readers understand how Planck measured the age and composition of the universe.