Sunset in Mars' Gale Crater

 

NASA's Curiosity Mars rover recorded this view of the sun setting at the close of the mission's 956th Martian day, or sol (April 15, 2015), from the rover's location in Gale Crater.

This was the first sunset observed in color by Curiosity. The image comes from the left-eye camera of the rover's Mast Camera (Mastcam). The color has been calibrated and white-balanced to remove camera artifacts. Mastcam sees color very similarly to what human eyes see, although it is actually a little less sensitive to blue than people are.

Dust in the Martian atmosphere has fine particles that permit blue light to penetrate the atmosphere more efficiently than longer-wavelength colors. That causes the blue colors in the mixed light coming from the sun to stay closer to sun's part of the sky, compared to the wider scattering of yellow and red colors. The effect is most pronounced near sunset, when light from the sun passes through a longer path in the atmosphere than it does at mid-day.

Image Credit: NASA/JPL-Caltech/MSSS
Explanation from: http://photojournal.jpl.nasa.gov/catalog/PIA19400

The Red Spider Nebula

Huge waves are sculpted in this two-lobed nebula some 3000 light-years away in the constellation of Sagittarius. This warm planetary nebula harbours one of the hottest stars known and its powerful stellar winds generate waves 100 billion kilometres high. The waves are caused by supersonic shocks, formed when the local gas is compressed and heated in front of the rapidly expanding lobes. The atoms caught in the shock emit the spectacular radiation seen in this image.

Image Credit: ESA & Garrelt Mellema
Explanation from: http://www.spacetelescope.org/images/heic0109a/

New stars around Westerlund 2

The red dots scattered throughout the cosmic landscape captured in this NASA/ESA Hubble Space Telescope image are a rich population of forming stars that are still wrapped in their gas and dust cocoons.

These stellar foetuses have not yet ignited the hydrogen in their cores to light-up as stars. However, Hubble’s near-infrared vision allows astronomers to identify these fledglings. The brilliant blue stars seen throughout the image are mostly in the foreground.

Image Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)
Explanation from: http://www.spacetelescope.org/images/heic1509f/

Hubble image of Messier 77

The NASA/ESA Hubble Space Telescope has captured this vivid image of spiral galaxy Messier 77 — a galaxy in the constellation of Cetus, some 45 million light-years away from us. The streaks of red and blue in the image highlight pockets of star formation along the pinwheeling arms, with dark dust lanes stretching across the galaxy’s starry centre. The galaxy belongs to a class of galaxies known as Seyfert galaxies, which have highly ionised gas surrounding an intensely active centre.

Image Credit: NASA, ESA & A. van der Hoeven
Explanation from: http://www.spacetelescope.org/images/heic1305a/