Lunar Eclipse Perspectives
5.02.2020

Do we all see the same Moon? Yes, but we all see it differently. One difference is the apparent location of the Moon against background stars -- an effect known as parallax. We humans use the parallax between our eyes to judge depth.

APOD: 2023 January 18 Б MACS0647: Gravitational Lensing of the Early Universe by Webb
18.01.2023

Gravitational lensing by the galaxy cluster MACS0647 -- in which the massive foreground cluster distorts and lenses the light emitted by distant background galaxies along the line of sight Б is on vivid display here in this recent multi-color infrared image from the James Webb Space Telescope (JWST).

Distortion from a Distant Cluster
23.08.2001

This stunning color deep sky view toward the constellation Pisces was made with data from a fast, sensitive, digital detector known as the Big Throughput Camera operating at Cerro Tololo Inter-American Observatory in Chile.

APOD: 2023 June 29 Б A Message from the Gravitational Universe
29.06.2023

Monitoring 68 pulsars with very large radio telescopes, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has uncovered evidence for the gravitational wave (GW) background by carefully measuring slight shifts in the arrival times of pulses. These shifts are correlated between different pulsars in a way that indicates that they are caused by GWs.

APOD: 2025 November 23 Б The Observable Universe
23.11.2025

How far can you see? Everything you can see, and everything you could possibly see, right now, assuming your eyes could detect all types of radiations around you -- is the observable universe. In light...

The Observable Universe
16.03.2022

How far can you see? Everything you can see, and everything you could possibly see, right now, assuming your eyes could detect all types of radiations around you -- is the observable universe. In light...

APOD: 2024 July 2 Б NGC 602: Oyster Star Cluster
2.07.2024

The clouds may look like an oyster, and the stars like pearls, but look beyond. Near the outskirts of the Small Magellanic Cloud, a satellite galaxy some 200 thousand light-years distant, lies this 5 million year old star cluster NGC 602.

Galaxy Cluster Abell 1689 Deflects Light
17.09.2013

It is one of the most massive objects in the visible universe. In this view from the Hubble Space Telescope's Advanced Camera for Surveys, Abell 1689 is seen to warp space as predicted by Einstein's theory of gravity -- deflecting light from individual galaxies which lie behind the cluster to produce multiple, curved images.

Cosmic Microwave Map Swirls Indicate Inflation
18.03.2014

Did the universe undergo an early epoch of extremely rapid expansion? Such an inflationary epoch has been postulated to explain several puzzling cosmic attributes such as why our universe looks similar in opposite directions.

Giant Cluster Bends, Breaks Images
14.06.1998

What are those strange blue objects? Many are images of a single, unusual, beaded, blue, ring-like galaxy which just happens to line-up behind a giant cluster of galaxies. Cluster galaxies here appear yellow and -- together with the cluster's dark matter -- act as a gravitational lens.