Looking at Mars at Night in UV


This obviously false color animation of Mars shows how its atmosphere glows and pulsates in ultraviolet light every night. It was assembled from months of data taken by the MAVEN spacecraft orbiting Mars. The nightglows occur three times during each rotation of the planet about 70 km above the surface. All three occur at sunset (which is on the left limb of the planet in this view). The pulsations are believed to be caused by downward winds creating nitric oxide in the atmosphere which glows in the UV spectrum. The fact that the three glows occur in data averaged over several months indicates that they are a nightly occurrence.

Video Credit: NASA

A Galaxy and a Star


This image taken by the Hubble Space Telescope show a galaxy cataloged as NGC 4907. Its about 270 million light-years away. The bright star in the image below the galaxy is in our galaxy. It appears to outshine the billions of stars in NGC 4907 because it is roughly 100,000 time closer to us.

Image Credit: NASA / ESA

This is Named for a Distant Cousin


hoag_hubble_960Is this one galaxy or two? That question came up back in 1950 when astronomer Art Hoag (a very distant relative) found this unusual extragalactic object. The ring full of bright blue stars surrounds a center of older, redder stars. The gap appears almost completely dark. How Hoag’s Object formed is unknown, but similar objects have now been identified and collectively labeled as a form of ring galaxy. Best guesses include a galaxy collision billions of years ago and the gravitational effect of a central bar that has since vanished. This photo was taken by the Hubble Space Telescope in 2001 and shows unprecedented details of Hoag’s Object. It spans about 100,000 light years and is around 600 million light years away toward the constellation of the Serpens (the Snake). Another ring galaxy is visible in the gap (at about one o’clock).

Image Credit: NASA

A 3D Model of the Helix Nebula


The Helix Nebula (aka NGC 7293) is a large planetary nebula located in the constellation Aquarius. It’s about 700 light-years away. The Helix Nebula has sometimes been referred to as the “Eye of God.” Tolkien fans have occasionally called it the “Eye of Sauron”

This animation of a 3-D model was created from Hubble Space Telescope and ground-based data of the Helix Nebula.

Credit: NASA, ESA, and G. Bacon (STScI)

A Doomed Dwarf


This is the dwarf galaxy known as NGC 1140. It lies 60 million light-years away in the constellation of Eridanus. It has an irregular form, much like the Large Magellanic Cloud, a small galaxy that orbits the Milky Way. This small galaxy is undergoing a starburst. Despite being only about one-tenth the size of the Milky Way, it is creating stars at about the same rate—the equivalent of one star the size of our sun being created per year. The galaxy is full of bright, blue-white, young stars.

Galaxies like NGC 1140 are of particular interest to astronomers because their composition makes them similar to the intensely star-forming galaxies in the early Universe, and those early Universe galaxies were the building blocks of present-day large galaxies like our Milky Way. Because they are so far away, the early Universe galaxies are harder to study, so these closer starbursting galaxies are a good substitute for studyingt galaxy evolution.

Its vigorous star formation eventually will have a very destructive effect on this small dwarf galaxy. When the larger stars in the galaxy die and explode as supernovae, the gas blown into space may escape the gravitational pull of the galaxy. The ejection of gas from the galaxy will starve future star formation. Thus, NGC 1140’s starburst cannot last for long.

Image Credit: ESA

Misplacing a Whole Galaxy


Messier_91_(M91)Messier 91 is a barred spiral galaxy located in the constellation Coma Berenices. It’s part of the Virgo Cluster of galaxies and is about 63 million light-years away from the Earth. It was the last of a group of eight nebulae discovered by Charles Messier in 1781. Originally, M91 was a missing object in the Messier catalogue as the result a bookkeeping mistake by Messier. It was not until 1969 that amateur astronomer William C. Williams realized that M91 was the galaxy that had also be cataloged as NGC 4548.

Image Credit: (CC) Joseph D. Schulman

Ganymede’s North Pole


On 26 December, 2019, the Juno spacecraft’s orbit around Jupiter brought it near the north pole of the ninth-largest object in the solar system, the moon Ganymede. The spacecraft’s Jovian Infrared Auroral Mapper (JIRAM) instrument took the first infrared images of the massive moon’s north pole.

Ganymede only moon in the solar system that is larger than the planet Mercury. It’s mostly water ice. It is also the only moon in the solar system with its own magnetic field. On Earth, the magnetic field provides a pathway for plasma (charged particles from the Sun) to enter our atmosphere and create aurora. Ganymede has no atmosphere to impede the progress of those charged particle, so the surface at its poles is constantly being bombarded by plasma from Jupiter’s gigantic magnetosphere. The bombardment has a dramatic effect on Ganymede’s ice.

The ice near both poles of the moon is amorphous. This is cause by the impact of the plasma on the surface. That pounding prevents the ice from having a crystalline structure.

Image Credit: NASA/ JPL / SWRI / ASI / INAF

The Crab’s Neutron Star


Heart of the CrabThis Hubble image peers deep into the core of the Crab Nebula, revealing its beating heart. At its center are the remnants of a supernova which sends out clock-like pulses of radiation and waves of charged particles. The neutron star at the very center of the Crab Nebula has about the same mass as the Sun, but it’s compressed into an incredibly dense sphere that is only a few miles across. Spinning 30 times a second, the neutron star ticks along, shooting out detectable beams of energy.

Image Credit: NASA / ESA

The Far Side


FarSideUVThe STEREO (Solar TErrestrial RElations Observatory) mission used a pair of spacecraft launched into orbit around the Sun. One slowly moved ahead of the Earth, and the other slowly lagged behind. Their separation allowed for simultaneous stereoscopic images to be taken of the Sun. The lagging spacecraft failed in 2014, but the leading spacecraft is still operational. This picture of the Sun was taken with the Extreme Ultraviolet Imager onboard the Solar TErrestrial RElations Observatory Ahead (STEREO-A) spacecraft. The spacecraft collects images in several wavelengths of light that are invisible to the human eye. This image shows the sun at a wavelength of 17.1 nm which which is usually coded in blue for false color imaging. STEREO-A is out of communication with the Earth when it’s on the far side of the Sun, where it operates in safe mode, collecting and saving data from its instruments. This image was taken by STEREO-A in July, 2015, from a point of view on the far side of the solar system as it had moved far enough around in its orbit to regain contact with the Earth.

Image Credit: NASA