APOD: 2025 July 17 Б 3I/ATLAS
17.07.2025

Discovered on July 1 with the NASA-funded ATLAS (Asteroid Terrestrial-impact Last Alert, System) survey telescope in Rio Hurtado, Chile, 3I/ATLAS is so designated as the third known interstellar object to pass through our Solar System It follows 1I/йOumuamua in 2017 and the comet 2I/Borisov in 2019.

Hubble's Constant And The Expanding Universe (I)
13.05.1996

Our Universe is expanding. Distant galaxies appear to recede from us at ever-increasing speeds. What is the rate of expansion? How long has it been expanding? What will be its ultimate fate? Two groups of astronomers are searching vigorously for answers to these fundamental questions using the Hubble Space Telescope (HST).

Magnetars In The Sky
26.11.2004

Indicated on this infrared image of the galactic center region are positions of candidate magnetars -- believed to be the strongest magnets in the galaxy. Classified by observers as Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs), these cosmic powerhouses are likely city-sized, spinning, highly-magnetized neutron stars. How strong is a magnetar's magnetic field?

Magnetars In The Sky
1.09.2001

Indicated on this infrared image of the galactic center region are positions of candidate magnetars -- believed to be the strongest magnets in the galaxy. Classified by observers as Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs), these cosmic powerhouses are likely city-sized, spinning, highly-magnetized neutron stars. How strong is a magnetar's magnetic field?

Hubble's Constant And The Expanding Universe (II)
14.05.1996

In this century, the discovery that the Universe is expanding has produced a revolution in human thought about the Cosmos. American astronomer Edwin Hubble played a major role in this profound discovery, coining the "Hubble constant".

Henrietta Leavitt Calibrates the Stars
3.09.2000

Humanity's understanding of the relative brightness and variability of stars was revolutionized by the work of Henrietta Swan Leavitt (1868-1921). Working at Harvard College Observatory, Leavitt precisely calibrated the photographic magnitudes of 47 stars to which all other stars could be compared.

Henrietta Leavitt Calibrates the Stars
27.10.1998

Humanity's understanding of the relative brightness and variability of stars was revolutionized by the work of Henrietta Swan Leavitt (1868-1921). Working at Harvard College Observatory, Leavitt precisely calibrated the photographic magnitudes of 47 stars to which all other stars could be compared.

At Work on Mars
14.07.1998

To learn about the history ofMars, just ask the rocks. Last year, that's exactly what the robot rover Sojourner did. Sojouner can be seen, above, analyzing a rock nicknamed Moe, trying to discern its past.

A Peculiar Cluster of Galaxies
29.09.1998

Far across the universe, an unusual cluster of galaxies has been evolving. A diverse group of galaxies populate this cluster, including, on the left, an unusual galaxy showing an equatorial polar ring and a large spiral. Above looms a large elliptical galaxy.

Tungurahua Erupts
2.04.2012

Volcano Tungurahua sometimes erupts spectacularly. Pictured above, molten rock so hot it glows visibly pours down the sides of the 5,000-meter high Tungurahua, while a cloud of dark ash is seen being ejected toward the left. Wispy white clouds flow around the lava-lit peak, while a star-lit sky shines in the distance.