A sweeping photograph combining one of Yellowstone National Park’s colorful hot springs with the star-filled Milky Way was selected as NASA’s Astronomy Picture of the Day for Aug. 16.
“Milky Way over Yellowstone,” photographed by astrophotographer Dave Lane, shows the Milky Way stretching across the night sky above Silex Spring in Wyoming’s Yellowstone National Park. The image is a 16-frame panorama captured in 2014 and combines two dramatically different natural features separated by an enormous difference in scale.
In the foreground is Silex Spring, a thermal feature roughly 10 meters, or about 33 feet, across. Steam rises from its heated water while its blue-green coloring contrasts with the dark landscape surrounding it.
Far beyond Earth, the Milky Way appears to arch from one side of the photograph to the other.
The glowing band is the plane of the galaxy viewed from inside it. Rather than being a cloud or atmospheric feature above Yellowstone, the band consists of the combined light of enormous numbers of distant stars and other material concentrated along the Milky Way’s galactic plane.
NASA featured Lane’s photograph through its long-running Astronomy Picture of the Day program, which publishes an astronomy-related image each day with an explanation prepared by professional astronomers.
The dramatic foreground exists because Yellowstone sits above one of the world’s best-known volcanic systems.
Heat associated with the Yellowstone hotspot powers the park’s geysers, hot springs, steam vents and mudpots. The U.S. Geological Survey says heat rising through Yellowstone’s crust maintains the hydrothermal system responsible for many of the park’s most recognizable features.
Microorganisms also play an important role in Yellowstone’s colorful thermal environments. The National Park Service says heat-loving microorganisms, known as thermophiles, can form vividly colored communities in and around hot springs, where temperature and chemistry create conditions in which specialized organisms thrive.
Silex Spring is part of the Fountain Paint Pot area in Yellowstone’s Lower Geyser Basin.
The photograph creates an unusual visual connection between processes occurring at vastly different distances: geothermal heat beneath the photographer’s feet and the structure of the Milky Way thousands of light-years away.
The Yellowstone hotspot has been active for millions of years. USGS research traces its influence across the western United States as the North American tectonic plate moved over the heat source, eventually producing the volcanic landscape associated with present-day Yellowstone.
Yellowstone experienced several enormous caldera-forming eruptions in its geologic past, including one about 640,000 years ago.
But federal scientists caution against interpreting Yellowstone’s volcanic history as evidence that another giant eruption is approaching.
The U.S. Geological Survey says the probability of another catastrophic caldera-forming eruption is exceedingly low and that Yellowstone Volcano Observatory monitoring has detected no signs suggesting an eruption is imminent. Scientists monitor earthquakes and changes in the ground using instruments including seismometers and GPS equipment.
If Yellowstone does erupt again, USGS says the most likely volcanic events are considerably smaller than a so-called supereruption. Hydrothermal explosions occur periodically in the park, while most of Yellowstone’s volcanic eruptions during the past 640,000 years have produced lava flows rather than enormous explosive events.
A future large caldera-forming eruption would nevertheless have widespread consequences. USGS says areas of Wyoming, Montana and Idaho closest to Yellowstone could experience pyroclastic flows, while ash could fall across other areas of the United States. A sufficiently large eruption could also affect global climate for years.
Federal scientists emphasize, however, that such an event is extremely unlikely on human timescales.
For Lane’s photograph, Yellowstone’s underground heat serves a much quieter purpose: sending steam across an illuminated spring beneath one of the clearest astronomical features visible from Earth.
The photograph was taken in 2014 and credited to Dave Lane. NASA Astronomy Picture of the Day editors Robert Nemiroff and Jerry Bonnell featured it on Aug. 16, 2026.
NASA’s original Astronomy Picture of the Day entry is available through the APOD archive.
