City Lights of Asia and Australia

This image of Asia and Australia at night is a composite assembled from data acquired by the Suomi NPP satellite in April and October 2012. The new data was mapped over existing Blue Marble imagery of Earth to provide a realistic view of the planet.

The nighttime view was made possible by the new satellite’s “day-night band” of the Visible Infrared Imaging Radiometer Suite. VIIRS detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe dim signals such as city lights, gas flares, auroras, wildfires, and reflected moonlight. In this case, auroras, fires, and other stray light have been removed to emphasize the city lights.

“Night time imagery provides an intuitively graspable view of our planet,” says William Stefanov, a scientist in NASA’s International Space Station program office who has worked with similar images from astronauts. “City lights are an excellent means to track urban and suburban growth, which feeds into planning for energy use and urban hazards, for studying urban heat islands, and for initializing climate models.”

Named for satellite meteorology pioneer Verner Suomi, NPP flies over any given point on Earth's surface twice each day at roughly 1:30 a.m. and p.m. The polar-orbiting satellite flies 824 kilometers (512 miles) above the surface, sending its data once per orbit to a ground station in Svalbard, Norway, and continuously to local direct broadcast users distributed around the world. The mission is managed by NASA with operational support from NOAA and its Joint Polar Satellite System, which manages the satellite's ground system.

Image Credit: NASA
Explanation from: https://earthobservatory.nasa.gov/NaturalHazards/view.php?id=79790

Herbig-Haro 502

The keen eye of the NASA/ESA Hubble Space Telescope has often peered deeply into the Orion Nebula to see the processes occurring there and revealed many dramatic tableaux of young stars hurling material into space and entire solar systems forming. This image shows the spectacular region around an object known as Herbig-Haro 502, a very small part of the vast stellar nursery.

The entire picture is filled with the rich colourful glow of the nebula and, just left of the centre, a star embedded in a pinkish glow can be also seen. This fascinating object is an example of a very young star surrounded by the cloud of gas from which it formed. This leftover material may accrete to form planets and eventually solar systems as intricate as our own. It is highly likely that the material that now forms our own planet Earth was part of a similar gaseous cocoon about five billion years ago. Such is the importance of these objects that much Hubble observing time has been dedicated to studying them.

In this image Herbig-Haro 502 shows up as a narrow pink jet extending away from the young star as well as curved bow shock features to the upper-right and lower-left. Herbig-Haro objects are striking areas of nebulosity near to recently formed stars. They are created when the very young stars eject gas at breakneck speeds of hundreds of kilometres per second, which impacts the surrounding gas and dust. These ephemeral shockwaves are thought to dissipate after a few thousand years; the blink of an eye in astronomical terms. They vary in size but are often much larger than our own Solar System.

At only around 1500 light-years distant, the Orion Nebula it is one of the closest areas of star formation to us. Understanding how stars form and evolve is an important area of astronomy, and one to which Hubble has greatly contributed. Images such as this are not only beautiful from an artistic perspective, but also help us understand more about how the Universe developed, and is continuing to change.

This image was taken with the Wide Field Channel of the Advanced Camera for Surveys on Hubble. This picture was created from images taken through filters that isolate the light from glowing hydrogen (F658N, coloured red), ionised oxygen (F502N, coloured green) and yellow light (F550W, coloured blue). The exposures times were 1000 s, 2000 s and 1000 s respectively. The field of view is about 3.3 arcminutes across.

Image Credit: ESA/Hubble & NASA
Explanation from: https://www.spacetelescope.org/images/potw1024a/

Saturn's moon Atlas

These raw, unprocessed images of Saturn's moon, Atlas, were taken on April 12, 2017, by NASA's Cassini spacecraft. The flyby had a close-approach distance of about 7,000 miles (11,000 kilometers).

These images are the closest ever taken of Atlas and will help to characterize its shape and geology. Atlas (19 miles, or 30 kilometers across) orbits Saturn just outside the A ring -- the outermost of the planet's bright, main rings.

Image Credit: NASA/JPL-Caltech/Space Science Institute
Explanation from: https://www.nasa.gov/feature/jpl/cassini-sees-flying-saucer-moon-atlas-up-close