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April 20 in spaceflight
Wikipedia records 6 spaceflight and astronomy events on April 20. Below are the pictures NASA published on April 20 in 6 different years — each one taken or released on this exact date.
Recorded events
IN THE RECORD6ENTRIES
Spaceflight and astronomy entries from Wikipedia's record of this date, oldest first — from 1865 onward.
Pictures from this date
PUBLISHED6IMAGES
NASA's Astronomy Picture of the Day for April 20, one per year. Some are public domain and some belong to the photographer — each says which.
Published on April 20
NASA’s Astronomy Picture of the Day, for this calendar date in each of the last several years.
2026
Comet R3 PanSTARRS over a Himalayan Valley
The best way to see comet R3 PanSTARRS’s long tail is with a camera. This week, the recently brightened comet appears in northern skies to the east just before dawn, but is only barely visible to the unaided eye. The many-degree ion tail captured on long duration camera exposures is not unusual for a comet - it is primarily due to the Earth's nearly sideways view of the tail as it points away from the Sun. In the featured image taken last week, Comet C/2025 R3 (PanSTARRS) showed off its flowing tail through a valley between two peaks in the Himalayan mountains of India. The comet passed its closest to the Sun yesterday. As it nears its closest approach to Earth next week, a bushy dust tail may become visible. The comet is slowly moving out of northern skies and by the end of the month will be visible after sunset in southern skies as it fades and leaves our Solar System. Growing Gallery: Comet R3 PanSTARRS in 2026
© Basudeb Chakrabarti & Samit Saha — used with the credit NASA publishes
2025
The Orion Nebula in Visible and Infrared
The Great Nebula in Orion is a colorful place. Visible to the unaided eye, it appears as a small fuzzy patch in the constellation of Orion. Long exposure, multi-wavelength images like this, however, show the Orion Nebula to be a busy neighborhood of young stars, hot gas, and dark dust. This digital composite features not only three colors of visible light but four colors of infrared light taken by NASA's orbiting Spitzer Space Telescope as well. The power behind much of the Orion Nebula (M42) is the Trapezium - four of the brightest stars in the nebula. Many of the filamentary structures visible are actually shock waves - fronts where fast moving material encounters slow moving gas. The Orion Nebula spans about 40 light years and is located about 1500 light years away in the same spiral arm of our Galaxy as the Sun.
© Infrared: NASA, Spitzer Space Telescope; Visible: Oliver Czernetz, Siding Spring Obs. — used with the credit NASA publishes
2024
Diamonds in the Sky
When the dark shadow of the Moon raced across North America on April 8, sky watchers along the shadow's narrow central path were treated to a total solar eclipse. During the New Moon's shadow play diamonds glistened twice in the eclipse-darkened skies. The transient celestial jewels appeared immediately before and after the total eclipse phase. That's when the rays of a vanishing and then emerging sliver of solar disk are just visible behind the silhouetted Moon's edge, creating the appearance of a shiny diamond set in a dark ring. This dramatic timelapse composite from north-central Arkansas captures both diamond ring moments of this total solar eclipse. The diamond rings are separated by the ethereal beauty of the solar corona visible during totality.
© Wright Dobbs — used with the credit NASA publishes
2023
The Dark Seahorse in Cepheus
Spanning light-years, this suggestive shape known as the Seahorse Nebula appears in silhouette against a rich, luminous background of stars. Seen toward the royal northern constellation of Cepheus, the dusty, obscuring clouds are part of a Milky Way molecular cloud some 1,200 light-years distant. It is also listed as Barnard 150 (B150), one of 182 dark markings of the sky cataloged in the early 20th century by astronomer E. E. Barnard. Packs of low mass stars are forming within, but their collapsing cores are only visible at long infrared wavelengths. Still, the colorful stars of Cepheus add to this pretty, galactic skyscape.
© Jeff Herman — used with the credit NASA publishes
2022
Planet Line over New York Bridge
There's an interesting sky to see if you wake up before the Sun. Lined up on toward the eastern horizon are four planets in a row. The planets are so bright they can even be seen from the bright sky inside a city. In fact, the featured image was taken from New York City, USA, with the foreground highlighted by the RFK (Triborough) Bridge. Pictured, the planets are, left to right, Jupiter, Venus, Mars, and Saturn. The planets all appear in a row because they all orbit the Sun in the same plane. This plane, called the ecliptic plane, was created in the early days of our Solar System and includes all planets, including Earth. The morning planet parade will continue throughout April and May, and will even be joined by Mercury in June. APOD volunteer programming opportunity: Discord
© Stan Honda — used with the credit NASA publishes
2021
Ingenuity: First Flight over Mars
What's the best way to explore Mars? Perhaps there is no single best way, but a newly demonstrated method shows tremendous promise: flight. Powered flight has the promise to search vast regions and scout out particularly interesting areas for more detailed investigation. Yesterday, for the first time, powered flight was demonstrated on Mars by a small helicopter named Ingenuity. In the featured video, Ingenuity is first imaged by the Perseverance rover sitting quietly on the Martian surface. After a few seconds, Ingenuity's long rotors begin to spin, and a few seconds after that -- history is made as Ingenuity actually takes off, hovers for a few seconds, and then lands safely. More tests of Ingenuity's unprecedented ability are planned over the next few months. Flight may help humanity better explore not only Mars, but Saturn's moon Titan over the next few decades.
NASA · public domain
What happened on April 20
1865
Astronomer Angelo Secchi demonstrates the Secchi disk, which measures water clarity, aboard Pope Pius IX's yacht, the L'Immaculata Concezion.
Angelo Secchi ↗
1945
Twenty Jewish children used in medical experiments at Neuengamme are killed in the basement of the Bullenhuser Damm school.
Nazi human experimentation ↗
1972
Apollo program: The Apollo 16 Lunar Module Orion, commanded by John Young and piloted by Charles Duke, lands on the Moon.
Apollo program ↗
2007
Johnson Space Center shooting: William Phillips barricades himself with a handgun in NASA's Johnson Space Center in Houston, Texas, before killing a male hostage and himself.
Johnson Space Center shooting ↗
2023
SpaceX's Starship launched for the first time before exploding four minutes into flight.
SpaceX ↗
2023
SpaceX's Starship rocket, the largest and most powerful rocket ever built, launches for the first time. It explodes four minutes into flight.
SpaceX Starship ↗
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.
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General-audience astronomy and spaceflight — none of it a textbook.
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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.
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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.
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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.
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