Launches
NO DATA0MISSIONS
The launch archive is still being mirrored, so this day has no launches listed yet.
ARCHIVE // DAY OF YEAR
July 21 in spaceflight
Wikipedia records 5 spaceflight and astronomy events on July 21. Below are the pictures NASA published on July 21 in 6 different years — each one taken or released on this exact date.
Recorded events
IN THE RECORD5ENTRIES
Spaceflight and astronomy entries from Wikipedia's record of this date, oldest first — from -356 onward.
Pictures from this date
PUBLISHED6IMAGES
NASA's Astronomy Picture of the Day for July 21, one per year. Some are public domain and some belong to the photographer — each says which.
Published on July 21
NASA’s Astronomy Picture of the Day, for this calendar date in each of the last several years.
2026
Turtle Rock on Mars
Is this a fossilized turtle on Mars? No. Although resembling a large Earth tortoise, this is a layered rock outcrop on Mars that is estimated to span about 15 meters, making it much larger than turtles on Earth. NASA’s robotic Curiosity rover came across this unusual mound, dubbed Miraflores, last month during its 4922nd Martian day exploring Mars. The small butte may survive because it was somehow more resistant to erosion than surrounding rock. More recent wind has now covered its top with orange Martian sand. Below the top shell, many layers of stratified rock are visible, possibly indicating a long history of intermittent wind-blown sand being deposited and then hardened by ground water. Similar wind-eroded layered landforms, such as yardangs in the Qaidam Desert of China, exist here on Earth. Curiosity and its companion rover Perseverance continue to investigate the ancient history of Mars as well as searching for signs of primeval life.
NASA · public domain
2025
Cat's Paw Nebula from Webb Space Telescope
Nebulas are perhaps as famous for being identified with familiar shapes as perhaps cats are for getting into trouble. Still, no known cat could have created the vast Cat's Paw Nebula visible toward the constellation of the Scorpion (Scorpius). At 5,700 light years distant, Cat's Paw is an emission nebula within a larger molecular cloud. Alternatively known as the Bear Claw Nebula and cataloged as NGC 6334, stars nearly ten times the mass of our Sun have been born there in only the past few million years. Pictured here is a recently released image of the Cat's Paw taken in infrared light by the James Webb Space Telescope. This newly detailed view into the nebula helps provide insight for how turbulent molecular clouds turn gas into stars. Explore Your Universe: Random APOD Generator
NASA · public domain
2024
King of Wings Hoodoo under the Milky Way
This rock structure is not only surreal -- it's real. Perhaps the reason it's not more famous is that it is smaller than one might guess: the capstone rock overhangs only a few meters. Even so, the King of Wings outcrop, located in New Mexico, USA, is a fascinating example of an unusual type of rock structure called a hoodoo. Hoodoos may form when a layer of hard rock overlays a layer of eroding softer rock. Figuring out the details of incorporating this hoodoo into a night-sky photoshoot took over a year. Besides waiting for a suitably picturesque night behind a sky with few clouds, the foreground had to be artificially lit just right relative to the natural glow of the background. After much planning and waiting, the final shot, featured here, was taken in May 2016. Mimicking the horizontal bar, the background sky features the band of our Milky Way Galaxy stretching overhead.
© Wayne Pinkston (LightCrafter Photography) — used with the credit NASA publishes
2023
Galactic Cirrus: Mandel Wilson 9
The combined light of stars along the Milky Way are reflected by these cosmic dust clouds that soar 300 light-years or so above the plane of our galaxy. Known to some as integrated flux nebulae and commonly found at high galactic latitudes, the dusty galactic cirrus clouds are faint. But they can be traced over large regions of the sky toward the North and South Galactic poles. Along with the reflection of starlight, studies indicate the dust clouds produce a faint reddish luminescence as interstellar dust grains convert invisible ultraviolet radiation to visible red light. Also capturing nearby Milky Way stars and distant background galaxies, this remarkably deep, wide-field image explores a complex of faint galactic cirrus known as Mandel Wilson 9. It spans over three degrees across planet Earth's skies toward the far southern constellation Apus.
© Gabriel Rodrigues Santos — used with the credit NASA publishes
2022
Messier 10 and Comet
Imaged on July 15 2022, comet C/2017 K2 (PanSTARRS) had a Messier moment, sharing this wide telescopic field of view with globular star cluster Messier 10. Of course M10 was cataloged by 18th century comet hunter Charles Messier as the 10th object on his list of things that were definitely not comets. While M10 is about 14 thousand light-years distant, this comet PanSTARRS was about 15 light-minutes from our fair planet following its July 14 closest approach. Its greenish coma and dust tail entertaining 21st century comet watchers, C/2017 K2 is expected to remain a fine telescopic comet in northern summer skies. On a maiden voyage from our Solar System's remote Oort Cloud this comet PanSTARRS was discovered in May 2017 when it was beyond the orbit of Saturn. At the time that made it the most distant active inbound comet known. Its closest approach to the Sun will be within 1.8 astronomical units on December 19, beyond the orbital distance of Mars.
© German Penelas Perez — used with the credit NASA publishes
2021
Colors: Ring Nebula versus Stars
What if you could see, separately, all the colors of the Ring? And of the surrounding stars? There's technology for that. The featured image shows the Ring Nebula (M57) and nearby stars through such technology: in this case, a prism-like diffraction grating. The Ring Nebula is seen only a few times because it emits light, primarily, in only a few colors. The two brightest emitted colors are hydrogen (red) and oxygen (blue), appearing as nearly overlapping images to the left of the image center. The image just to the right of center is the color-combined icon normally seen. Stars, on the other hand, emit most of their light in colors all across the visible spectrum. These colors, combined, make a nearly continuous streak -- which is why stars appear accompanied by multicolored bars. Breaking object light up into colors is scientifically useful because it can reveal the elements that compose that object, how fast that object is moving, and how distant that object is.
NASA · public domain
What happened on July 21
-356
The Temple of Artemis in Ephesus, one of the Seven Wonders of the World, is destroyed by arson.
Temple of Artemis ↗
1961
Mercury program: Mercury-Redstone 4 mission: Gus Grissom piloting Liberty Bell 7 becomes the second American to go into space (in a suborbital mission).
Project Mercury ↗
1969
Apollo program: At 02:56 UTC, astronaut Neil Armstrong becomes the first person to walk on the Moon, followed 19 minutes later by Edwin "Buzz" Aldrin.
Apollo program ↗
1983
The world's lowest temperature in an inhabited location is recorded at Vostok Station, Antarctica at −89.2 °C (−128.6 °F).
Lowest temperature recorded on Earth ↗
2011
NASA's Space Shuttle program ends with the landing of Space Shuttle Atlantis on mission STS-135 at NASA's Kennedy Space Center.
NASA ↗
Sources and licences
Event text and thumbnails come from Wikipedia and are used under CC BY-SA 4.0. Images are drawn only from Wikimedia Commons, which does not accept non-free content — each thumbnail links to its file page, where its licence and author are recorded.
Launch records are from The Space Devs’ Launch Library 2. This archive is still being mirrored, so some days are incomplete. Pictures are NASA’s Astronomy Picture of the Day; NASA imagery is generally not subject to copyright, but individual APOD entries are frequently the property of the photographer, and each caption says which applies.
FIELD KIT / LIBRARY
SPONSORED
General-audience astronomy and spaceflight — none of it a textbook.
As an Amazon Associate I earn from qualifying purchases. Links here cost you nothing extra.
- VIEW
LISTING
Cosmos — Carl Sagan
Still the best single argument for why any of this matters, and it leaves the arithmetic in. For a reader who wants the science, not just the awe.
- VIEW
LISTING
Pale Blue Dot — Carl Sagan
The case for leaving Earth, written by someone unsentimental about how hard that is. Suits readers who want the argument rather than the poster.
- VIEW
LISTING
Project Hail Mary — Andy Weir
Hard-SF problem solving in The Martian's key — for anyone who liked the engineering more than the peril. The only novel on this list.
BROWSE opens an Amazon search, not a specific recommendation.
LINKS AMAZON.COM