Note that on this composite, the planets are not to scale. In reality, the diameter of Mars is less than 1/20th that of Jupiter, or about the size of Ganymede’s shadow. Saturn is about 85% of the diameter of Jupiter—about 1.5 times larger than shown here. 

Hubble Space Telescope
Mars 2016
Although Hubble is not designed to observe solar eclipses, it can be used to record other types of planetary alignments in the Solar System. Sunlight reflects off bright clouds above the volcanoes, ice caps, impact craters, and ancient stream valleys that cover the rusty surface of Mars. Mars is best viewed during opposition, when the Sun is on the opposite side of Earth. During opposition, the entire nearside of a planet is illuminated and the planet is about as close as it can be to Earth.

Instrument: WFC3/UVIS
Exposure Date: May 12, 2016
Filters and Color Assignments:
Purple: 275nm
Blue: 410nm
Green: 502nm
Red: 673nm

Hubble Space Telescope
Jupiter 2014
The shadow of Jupiter’s largest moon, Ganymede, sweeps across the giant storm known as the Great Red Spot. The area in shadow—the pupil in the eyeball of the Great Red Spot—experiences a total solar eclipse as Ganymede passes in front of the Sun.

Instrument: WFC3/UVIS
Exposure Date: April 21, 2014
Filters and Color Assignments:
Blue: 395 nm
Green: 502 nm
Red: 631 nm

Hubble Space Telescope
Saturn 2009
Two moons chase their shadows across Saturn as they transit the planet: Titan, the largest, near the top and the much smaller Mimas, just above the rings on the left. Saturn’s rings also reflect sunlight and cast their own shadows, visible as a sliver above the foreground ring.

Instrument: WFPC2
Exposure Date: February 24, 2009
Filters and Color Assignments:
Blue: 439 nm (B)
Green: 555 nm (V)
Red: 675 nm (R)

Credit: NASA, ESA, L. Frattare (STScI), A. Simon (Goddard Space Flight Center), C. Go (Philippines), M.H. Wong (STScI/UC Berkeley), and the Hubble Heritage Team (STScI/AURA)

Zolt Levay
Lunar Eclipse
Columbia, Maryland ǀ 2010

A sequence of exposures, taken over several hours on the December solstice of 2010, captures the Moon as it passes through Earth’s shadow. During the deepest phase of the eclipse, the Moon is illuminated only by sunlight that has passed through Earth’s atmosphere. While blue light is scattered in all directions by the atmosphere, red light bends inward toward the Moon, giving the Moon its rusty red hue.

Camera: Nikon D300
Lens: Nikon 80–400 mm; f/4.5–5.6
Exposure: 400 mm; composite of 13 exposures
Exposure Date: December 21, 2010

Zolt Levay
Sunset at Tsegi Overlook
Canyon de Chelly National Monument, Arizona ǀ 2014

As Earth rotates, the Sun sets and the shadow of the western wall of Canyon de Chelly flows over the canyon floor and up the 280-million-year-old layers of wind-blown sand that form this portion of the Colorado Plateau.

Exposure Date: October 2, 2014
Camera: Nikon D800
Lens: Nikon 24–85 mm; f/2.8–4
Exposure: 42 mm; f/6.7; 4 sec; ISO 800

Hubble Space Telescope
The Bubble Nebula, NGC 7635
Cassiopeia ǀ 2016

The Bubble Nebula is an expanding sphere of glowing gas, expelled and illuminated by a central star nearly half-a-million times as luminous as the Sun. The colors represent various elements glowing at different temperatures. Hot oxygen of the bubble glows blue. Cooler hydrogen and nitrogen glow green and red, the colors combining to form the yellow of the dense pillars of gas and dust beyond the bubble.

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Exposure Date: February 25/26, 2016
Instrument: WFC3/UVIS
Exposure Time: 3.5 hours
Filters and Color Assignments:
Blue: 502 nm (oxygen)
Green: 656 nm (hydrogen)
Red: 658 nm (nitrogen)

Zolt Levay
Chromatic Spring
Yellowstone National Park, Wyoming ǀ 2011

Sunlight interacts with water, bacteria, and rock to form concentric rings of color surrounding the deep vent of a hot spring, where rainwater, heated by magma deep underground, wells up from below.

Exposure Date: September 1, 2011
Camera: Nikon D300,

Lens: Nikon 10–24 mm; f/3.5–4.5
Exposure: 10 mm; f/16; 1/125 sec; ISO 200

Hubble Space Telescope
The Butterfly Nebula, NGC 6302
Scorpius ǀ 2009

Hidden in the dusty thorax of this celestial butterfly is a dying star. Nearly 4,000 light-years from Earth, the star—one of the hottest known in the Milky Way—is revealed by its interactions with the silhouetted dust and glowing gas that surround it. Both the donut-shaped ring of dust and the wings of searing hot gas were blown out of the outer layers of the star. The finger-like details on the wings are denser regions of gas shaped by winds of charged particles streaming from the star.

Credit: NASA, ESA, and the Hubble SM4 ERO Team

Exposure Date: July 27, 2009
Instrument: WFC3/UVIS
Exposure Time: 6.5 hours
Filters and Color Assignments:
White: 673 nm (sulfur)
Orange: 658 nm (nitrogen)
Brown: 656 nm (hydrogen)
Cyan: 502 nm (oxygen)
Blue: 469 nm (helium)
Purple: 373 nm (oxygen)

Zolt Levay
Castle Geyser
Yellowstone National Park, Wyoming ǀ 2011

Scalding hot vapor condenses to form clouds that block the Sun, casting small shadows over Castle Geyser in Yellowstone National Park. Sunlight shines brightly through the less dense, translucent portions of the cloud, and reflects off large sparkling beads of liquid water shooting up from the geyser vent.

Exposure Date: September 2, 2011
Camera: Nikon D300
Lens: Nikon 24–85 mm; f/2.8–4
Exposure: 24 mm; f/13; 1/2000 sec; ISO 200

Hubble Space Telescope
The Eagle Nebula, M16
Serpens ǀ 2015

The iconic Pillars of Creation—immense towers of cold dust and gas bathed in ultraviolet radiation—were originally photographed by Hubble in 1995. This new image, captured during 30 hours of exposure time in 2014, takes advantage of the higher resolution and greater sensitivity afforded by upgrades made to Hubble during its fifth and final servicing mission by astronauts in 2009. In the visible light seen here, the densest portions of the pillars are opaque, absorbing the surrounding light, hiding the stars beyond as well as those forming within. Glowing streamers of hot gas move out from the pillars as they are slowly eroded by starlight from above.

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Exposure Date: September 2014
Instrument: WFC3/UVIS
Exposure Time: 30.5 hours
Filters and Color Assignments:
Blue: 502 nm (oxygen)
Green: 657 nm (hydrogen + nitrogen)
Red: 673 nm (sulfur)

Zolt Levay
Delicate Arch Sunburst
Arches National Park, Utah ǀ 2017 An arch of durable sandstone that has survived millions of years of assault by wind and running water partially eclipses the Sun at Arches National Park. In this untraditional perspective, the famous arch looks much narrower than it actually is. Interactions between light and the camera lens create the starburst effect that gives the illusion that the Sun is in the foreground.

Exposure Date: April 26, 2017
Camera: Nikon D800
Lens: Nikon 10–24 mm; f/3.5–4.5
Exposure: 10 mm; f/22; 1/320 sec; ISO 200

Hubble’s near-infrared camera allows us to see into dust clouds and beyond the dust and gas of the Eagle Nebula, into deeper space. Hubble Space Telescope, 2014. NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Light, Shadows, and Silhouettes
Most of what we know about the universe beyond Earth is based on observations of electromagnetic radiation, better known simply as light. Whether captured by a telescope in space or a camera on Earth’s surface, light, shadows, and silhouettes reveal interactions between energy and matter, forming snapshots of the dynamic processes shaping our universe. In the Eagle Nebula 6,500 light-years from Earth, what appear at first to be billowing clouds of smoke or giant rocky protrusions are actually the eroded remains of dense towers of dust and gas, silhouetted against starlight and hot glowing gas. Like rock formations that have been sculpted by millions of years of wind and water, the iconic Pillars of Creation have also been shaped by outside forces. Ultraviolet radiation, combined with the force of charged particles hurtling through space, have eroded the cloud, leaving behind denser, more resistant remains. Though these structures are immense—with heights hundreds of thousands of times the distance from Earth to the Sun—the stellar winds will have completely eroded them away several million years from now, exposing the stars that are currently forming deep inside. Our ability to perceive objects and materials in the universe depends on the type of light we can observe. In visible light, the densest portions of the pillars are opaque, absorbing the surrounding light, hiding the stars beyond as well as those forming within. With NASA’s next generation of more sensitive infrared telescopes, the Webb Telescope and WFIRST, we will be able to peer even deeper into the shadows of dust to directly photograph stars in the process of being born.
WFIRST

Artist’s Conception
Wide Field Infrared Survey Telescope (WFIRST)
Scheduled for launch in the mid-2020s, WFIRST is designed to answer essential questions about dark energy, exoplanets, and infrared astrophysics. WFIRST’s Wide Field instrument will allow us to produce Hubble-quality images over a field of view 100 times greater than Hubble, enabling us to map great swaths of the sky in infrared light and better understand the array of objects in the universe. The telescope’s coronagraph will be used to eclipse starlight, allowing us to study planets orbiting other stars.

Credit: NASA
Find out more

JWST

Artist’s Conception
James Webb Space Telescope

In the fall of 2018, NASA’s next Great Observatory, the James Webb Space Telescope, will join Hubble in space. Designed to collect infrared light, Webb will allow us to investigate parts of the universe that are currently too far or faint to detect, or that shine in light that is invisible to our eyes and to Hubble. With its 256-inch gold-coated mirror and tennis-court-sized shade to protect it from the Sun, Webb will be able to peer through the dust to study the formation of stars and planets; examine the atmospheres of planets orbiting other stars; and look billions of years back in time to further explore our cosmic origins.

Credit: NASA
Find out more


Hubble Space Telescope
The Sombrero Galaxy, M104
Virgo ǀ 2003

Nearly 30 million light-years away and 50,000 light-years across, the bright Sombrero Galaxy looks like a cross between a flat disk galaxy and a spheroidal elliptical galaxy. Seen nearly edge-on, our view of this galaxy’s ghostly halo and bright, diffuse central bulge is partially eclipsed by shadowy rings of dust that scatter and absorb light emitted by stars and gas.

Credit: NASA and The Hubble Heritage Team (STScI/AURA)
Exposure Date: May–June 2003
Instrument: ACS/WFC
Exposure Time: 10.2 hours
Filters and Color Assignments:
Blue: 435 nm (B)
Green: 555 nm (V)
Red: 625 nm (r)

Zolt Levay
Milky Way over Jackson Lake
Grand Teton National Park, Wyoming ǀ 2016

The eruption of light from the peaks of the Tetons marks the bright center of our own barred spiral galaxy, the Milky Way. From our position within the galaxy disk, roughly 30,000 light-years from the center, we are only able to see the structure of the galaxy edge-on. The colorful backdrop is actually foreground light known as airglow, emitted by chemical reactions in Earth’s atmosphere.

Exposure Date: July 14, 2016
Camera: Nikon D800
Lens: Nikon 15 mm; f2/8
Exposure: 30 sec; ISO 6400

Hubble Space Telescope
NGC 1300
Eridanus ǀ 2005

Seen face-on, NGC 1300 is the defining example of a class of galaxies known as barred spirals. Unlike a typical spiral, whose arms curve directly out from the center, the arms of a barred spiral begin at either end of a central rod-shaped mass of stars. Dark lanes of dust weave through the bright clusters of stars and glowing gas, tracing the structure of the arms, bar, and tight spiral-shaped nucleus at the center. Adorning the background of this image is the light of more distant galaxies.

Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

Exposure Date: September 2004
Instrument: ACS/WFC
Filters and Color Assignments:
Blue: 435 nm (B)
Green: 555 nm (V)
Red: 814 nm (I) + 658 nm (hydrogen + nitrogen)

Hubble Space Telescope
Stephan’s Quintet, HCG 92
Pegasus ǀ 2009 In the center of a group of galaxies known as Stephan’s Quintet, two bright bulbs mark the cores of two galaxies colliding, their interaction resulting in the formation of new stars. The mutual gravitational attraction between this pair and the barred spiral above has further distorted these galaxies. The bluer spiral galaxy has escaped the fray—unaffected because it is actually part of the foreground, a dwarf galaxy 250 million light-years closer to us than the others, and not actually part of the group.

Credit: NASA, ESA, and the Hubble SM4 ERO Team

Exposure Date: July/August, 2009
Instrument: WFC3/IR and WFC3/UVIS
Exposure Time: 23 hours
Filters and Color Assignments:
Blue: 438 nm (B)
Green: 606 nm (V)
Red: 140 nm (JH) + 657 nm (hydrogen + nitrogen) + 665 nm (hydrogen + nitrogen) + 814 nm (I)

Zolt Levay
Milky Way over Mesa Arch
Canyonlands National Park, Utah ǀ 2017

The disk of the Milky Way forms an arc of light over Mesa Arch, a sandstone formation illuminated by studio lights from below. Our view of the Milky Way changes from hour to hour as Earth rotates, and from month to month as Earth orbits the Sun. It will also change over millions of years as the Solar System orbits the center of the galaxy, and over billions of years as the Milky Way begins to merge with its neighboring galaxy, Andromeda.

Exposure Date: April 26, 2017
Camera: Nikon D800
Lens: Nikon 20 mm; f/1.8
Exposure: 20 sec; ISO 1600; panorama of four frames

Hubble Space Telescope
The Hubble Ultra Deep Field 2014
Fornax ǀ 2014

Probing deep into the cosmos, the Hubble Ultra Deep Field is one of the greatest legacies of the Hubble Space Telescope. By combining ultraviolet, visible, and near-infrared light captured over the course of 600 hours of exposure time between 2002 and 2012, roughly 10,000 galaxies become visible in a patch of sky less than one-tenth the diameter of the full Moon.

The extraordinary depth of field allows us to peer more than 13 billion light-years through space and time: from foreground stars in our Milky Way; past mature galaxies relatively nearby, and developing galaxies in the mid-field; to small, reddish infant galaxies more than 10 billion light-years away.

NASA’s future infrared survey telescope, WFIRST, will give us the ability to produce detailed images like this, but over patches of sky 100 times larger, providing an even more complete census of galaxies in the universe.

Credit: NASA, ESA, H. Teplitz and M. Rafelski (IPAC/Caltech), A. Koekemoer (STScI), R. Windhorst (Arizona State University), and Z. Levay (STScI)
Exposure Date: July 2002–September 2012 (not continuous)
Instrument: ACS/SBC, WFC3/UVIS, ACS/WFC, and WFC3/IR
Exposure Time: ~600 hours
Filters and Color Assignments:
Blue: ACS/SBC 150LP, WFC3/UVIS 225 nm (U) + 275 nm (U) + 336 nm (U), ACS/WFC 435 nm (B) + 606 nm (V) +
Green: ACS/WFC 775 nm (I) + 814 nm (I) + 850LP (z), WFC3/IR 105 nm (Y)
Red: WFC3/IR 125 nm (J) + 140 nm (JH) + 160 nm (H)

Zolt Levay
Star Trails over the Mittens
Monument Valley Navajo Tribal Park, Arizona ǀ 2016

Eroded remains of the Colorado plateau are silhouetted against the fall night sky along the Colorado-Arizona border. The bright patch over the left butte is the Pleiades star cluster, a group of roughly 3,000 stars just 400 light-years away. The star trails are an artifact of Earth’s rotation: this photograph is a composite of 59 exposures of 20 seconds each.

Exposure Date: October 4, 2016
Camera: Nikon D800
Lens: Nikon 20 mm; f/1.8
Exposure: 20 sec; ISO 3200; composite of 59 exposures

Hubble Space Telescope
Cerro Tololo Inter-American Observatory (Chile)
The Carina Nebula, NGC 3372
Carina ǀ 2007 A mosaic of 48 images forms a panorama spanning 50 light-years across the central region of one of the largest known star-birth regions in the Milky Way.

The shadowy pillars and globules silhouetted against starlight and glowing gas are dense regions of cold gas and dust that have resisted the erosive power of ultraviolet radiation and stellar winds emitted by the young, bright stars nearby. The interaction with high-energy starlight also causes the vapory glow that surrounds the dusty clouds. In places, bright jets of gas spew out of the pillars, evidence that newly formed stars are hidden within. Even the smallest nodules in this landscape are large enough to hold entire solar systems. On the left, the bright young star Eta Carinae, 100 times as massive as the Sun and five million times more luminous, is in the process of expelling its outer layers and preparing for its eventual demise in a supernova explosion.

Credit: NASA, ESA, N. Smith (University of California, Berkeley), NOAO/AURA/NSF, and The Hubble Heritage Team (STScI/AURA)

Exposure Date: March–July 2005 (HST), December 2001–March 2003 (CTIO)
Instrument: HST: ACS; CTIO: 4m Blanco Telescope and CTIO: MOSAIC2
Filters and Color Assignments:
Luminosity: 658 nm (hydrogen + nitrogen)
Blue: CTIO 501 nm (oxygen)
Green: CTIO 658 nm (hydrogen + nitrogen)
Red: CTIO 672 nm + 673 nm (sulfur)

This image was made by combining brightness information from Hubble with color observations from a ground-based telescope.

Zolt Levay
Mountain Sunset
Rocky Mountain National Park, Colorado ǀ 2015

Clouds simultaneously block sunlight scattered from the sky above, while reflecting light from the Sun as it sets below the horizon. In contrast to the true glow of hot gas in a celestial landscape, the orange glow of sunset is not given off by the atmosphere. It is instead caused by scattering of some colors of sunlight and absorption of other colors as light passes through the atmosphere.

Exposure Date: July 19, 2015
Camera: Nikon D300
Lens: Nikon 80–400 mm; f/4.5–5.6
Exposure: 80 mm; f/7.1; 1/50 sec; ISO 400

Hubble Space Telescope
NGC 3324
Carina ǀ 2008

A resistant ridge of dense gas and dust lines a giant gas-filled cavity in the Carina Nebula 7,200 light-years away. Like mountain ranges on Earth, the ridge has been sculpted by natural forces. A cluster of young hot stars above the scene has carved out the cavity and continues to erode peaks and valleys with ultraviolet radiation and streams of charged particles. Evidence of the interactions can be seen in the ghostly streamers of vapor rising out of the landscape.

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Exposure Date: March 2006 and July 2008
Instrument: ACS/WFC; WFPC2
Exposure Time: 2 hours
Filters and Color Assignments:
Blue: 502 nm (oxygen)
Green: 658 nm (hydrogen + nitrogen)
Red: 673 nm (sulfur)

Zolt Levay
Star Trails over Towers of the Virgin
Zion National Park, Utah ǀ 2014

Combining 33 one-minute exposures turns points of light into arcs, and night into day. The bright light illuminating the sedimentary rocks at Zion National Park is not direct sunlight, but is rather the reflected light of the nearly full Moon. The illusion is given away by the trails of stars that are not visible in the bright light of day.

Exposure Date: October 6, 2014
Camera: Nikon D800
Lens: Nikon 10–24 mm; f/3.5–4.5
Exposure: 10 mm; f/5.6; 60 sec; ISO 400; composite of 33 exposures

Hubble Space Telescope
The Veil Nebula, NGC 6960
Cygnus ǀ 2015

Blue oxygen, green sulfur, and red hydrogen combine to form a rippling curtain of glowing gas that makes up the Veil Nebula, also called the Cygnus Loop. The nebula is a supernova remnant, the remains of a star that exploded in the Milky Way several thousand years ago. The dust and gas that make up the nebula were expelled by the star before it exploded. The light they emit now is a result of being shocked and heated by the supernova blast wave, which is still moving through space at more than a million miles per hour. What we see here is a small detail of a much larger, spherical structure.

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Exposure Date: April 14–17, 2015
Instrument: WFC3/UVIS
Filters and Color Assignments:
Blue: 502 nm (oxygen)
Red: 657 nm (hydrogen + nitrogen)
Green: 673 nm (sulfur)
Blue: 555 nm (V)
Red: 814 nm (I)

Zolt Levay
Sunrise at Lower Yellowstone Falls
Yellowstone National Park, Wyoming ǀ 2011

Light from the rising Sun reflects off mist and layers of soft volcanic rock carved by the Yellowstone River.

Exposure Date: August 30, 2011
Camera: Nikon D800
Lens: Nikon 24–85 mm; f/2.8–4
Exposure: 48 mm; f/11; 1/60 sec; ISO 200

Hubble Space Telescope
Pillars in the Eagle Nebula, M16
Serpens ǀ 2005

Silhouetted against the blue glow of oxygen and red glow of hydrogen, a spire of cold gas and dust rises nearly 10 light-years high in the Eagle Nebula 6,500 light-years from Earth. Visible light reflects off the dust in the spire, while higher energy ultraviolet light heats up the material, causing the glow around the edges. The ultraviolet radiation from hot young stars above the spire is also partially responsible for driving material off the spire and sculpting it into its present form. Newly forming stars are likely to be hidden deep within the spire, obscured by dust.

Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)
Exposure Date: November 4–7, 2004
Instrument: ACS/WFC
Exposure Time: 3.4 hours
Filters and Color Assignments:
Blue: 435 nm (B) + 502 nm (oxygen)
Green: 555 nm (V) + 658 nm (hydrogen + nitrogen) + 502 nm (oxygen)
Red: 658 nm (hydrogen + nitrogen) + 814 nm (I)

Zolt Levay
Horsetail Fall
Yosemite National Park, California ǀ 2009

As in celestial images, it can be difficult to distinguish the reflection of starlight off an object from the glow, or emission of light, from the object itself. Here in Yosemite, what appears to be a glowing river of lava is actually water, illuminated by the setting Sun. The effect is caused by a fortuitous alignment of the direction of the Sun and the location of the falls along the rock face.

Exposure Date: February 27, 2009
Camera: Nikon D800
Lens: Nikon 80–400 mm; f/4.5–5.6
Exposure: 122 mm; f/16; 1/125 sec; ISO 200

Hubble Space Telescope
The Cigar Galaxy, M82
Ursa Major ǀ 2006

Shredded cloud-like plumes of glowing hydrogen gas jet out of the bright blue disk of a nearby starburst galaxy, where stars are forming 10 times faster than in the Milky Way. The exceedingly rapid rate of star formation is partially powered by the stars themselves: The winds of existing stars blow outward, compressing surrounding clouds of gas and causing them to collapse to form new stars. Hidden deep near the center of the galaxy are two black holes, evident as bright sources of X-ray light that are invisible to Hubble, but can be detected by other types of space telescopes.

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Exposure Date: March 27–29, 2006
Instrument: ACS/WFC
Exposure Time: 13.7 hours
Filters and Color Assignments:
Blue: 435 nm (B)
Green: 555 nm (V)
Red-orange: 658 nm (hydrogen)
Red: 814 nm (I)

Zolt Levay
Milky Way over Bear Lake
Rocky Mountain National Park, Colorado ǀ 2015

The bright disk of the Milky Way silhouettes mountain peaks and reflects off the still water of Bear Lake in Rocky Mountain National Park. While the small horizontal shadow just above the center peak is a cloud in our atmosphere, the wispy shadows interlaced with the galactic lights are made of interstellar dust. As in other galaxies, dust eclipses the light of more distant stars.

Exposure Date: July 18, 2015
Camera: Nikon D800
Lens: Nikon 18–35 mm; f/3.5–4.5
Exposure: 18 mm; f/4; 30 sec; ISO 6400


Hubble Space Telescope
Arp 273
Andromeda ǀ 2011

The peculiar rose shape of this double galaxy 340 million light-years away is a result of the gravitational pull between the two galaxies as they move through and past each other in space. The smaller galaxy seems to have taken a dive through the larger spiral—distorting both—and inciting an episode of intense star formation that lights up its nucleus. Prominently adorning the arms are large blue clusters of young, hot stars glowing brightly in ultraviolet light. The smaller red lights are older, cooler stars.

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Exposure Date: December 17, 2010
Instrument: WFC3/UVIS
Exposure Time: 5.9 hours
Filters and Color Assignments:
Blue: 390 nm (U)
Green: 475 nm (g)
Red: 600LP (Red Longpass)

Zolt Levay
Star Trails over Fall Foliage
Shenandoah National Park, Virginia ǀ 2015

Although the stars that make up the Milky Way and other galaxies do move over time, the star trails we see here reflect apparent motion. As Earth rotates, the stars appear to move in arcs around Polaris, the North Star. Combining a series of long exposures shot over the course of 20 minutes gives the illusion of daylight, as well as motion. In fact, the sky and forest are illuminated by the first quarter Moon.

Exposure Date: October 23, 2015
Camera: Nikon D800
Lens: Nikon 10–20 mm; f/3.5–4.5
Exposure: 10 mm; f/4; 10 sec; ISO 1600; composite of 117 frames

A galaxy cluster acts like a giant lens, distorting and magnifying the light from distant galaxies.

Hubble Space Telescope
Gravitational Lensing around Abell 370
Cetus ǀ 2017

The galaxy cluster Abell 370 acts as a natural telephoto lens, magnifying and distorting the images of more distant galaxies. The cluster itself is 4 billion light-years away and is made of several hundred galaxies, including large yellowish elliptical galaxies, and smaller, bluer spirals. The lensed galaxies, some of which appear as arcs around the cluster, are estimated to be between five and nearly 13 billion light-years away. Much of the magnifying power of this cluster is due to dark matter, a mysterious substance that does not cast shadows, form silhouettes, or glow in any form of light. Its presence is evident only in its gravitational influence on other objects.

Credit: NASA, ESA, and J. Lotz and the Hubble Frontier Fields Team (STScI)
Exposure Date: September 2009–February 2015 (not continuous)
Instrument: ACS/WFC; WFC3/IR
Filters and Color Assignments:
Blue: 435 nm + 606 nm
Green: 814 nm + 105 nm
Red: 125 nm + 140 nm + 160nm

Zolt Levay
Moonlit Dunes
Great Sand Dunes National Park, Colorado ǀ 2016

The reflected sunlight of the first quarter Moon illuminates the shifting sands of a dune field before a backdrop of stars in the Milky Way. Only a few thousand of the several hundred billion stars that make up the Milky Way are visible to the naked eye. With more than 1,000 billion galaxies, most containing billions to trillions of stars, scientists estimate that there are more stars in the universe than grains of sand on Earth’s surface.

Exposure Date: October 7, 2016
Camera: Nikon D800
Lens: Nikon 20 mm; f/1.8
Exposure: 10 sec; ISO 3200

Nature's Lenses
The arcs of light that ring the center of this Hubble image could easily be mistaken for star trails, glass lens effects, or telescope imperfections. In fact, what we see is not the result of motion of the galaxies, rotation of the telescope, or distortions of light within the telescope. It is actually the mass of an enormous cluster of galaxies—with each individual galaxy made of billions of stars—that behaves like a giant magnifying glass, distorting and amplifying the light of much more distant galaxies behind it. This effect, known as gravitational lensing, was predicted by Albert Einstein as part of his general theory of relativity. Einstein calculated that starlight should curve as it passes close by massive objects like the Sun. As a result, the positions of the stars appear to shift slightly as the Sun crosses the sky. It was during a total solar eclipse on May 29, 1919 that scientists first successfully tested the theory. With masses upward of millions of billions times that of the Sun, galaxy clusters like Abell 370 warp space in a much more dramatic way than a single star, magnifying entire galaxies and allowing us to see much deeper into the universe than would otherwise be possible. The power of Hubble combined with nature's lenses provides the farthest glimpses of our universe, a view that will be extended further when NASA's next Great Observatory, the James Webb Space Telescope, launches in late 2018.