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October 6 in spaceflight
Wikipedia records 5 spaceflight and astronomy events on October 6. Below are the pictures NASA published on October 6 in 5 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 1915 onward.
Pictures from this date
PUBLISHED5IMAGES
NASA's Astronomy Picture of the Day for October 6, one per year. Some are public domain and some belong to the photographer — each says which.
Published on October 6
NASA’s Astronomy Picture of the Day, for this calendar date in each of the last several years.
2025
The Changing Ion Tail of Comet Lemmon
How does a comet tail change? It depends on the comet. The ion tail of Comet C/2025 A6 (Lemmon) has been changing markedly, as detailed in the featured image sequenced over six days between September 25 and October 4 (left to right) from Texas, USA. On some days, the comet's ion tail was relatively more complex than other days. Reasons for tail changes include the rate of ejection of material from the comet's nucleus, the strength and complexity of the passing solar wind, and the rotation rate of the comet. Sometimes, over the course of a week, apparent differences even result from a change of perspective from the Earth. In general, a comet's ion tail will point away from the Sun, as gas expelled is pushed out by the Sun's wind. Comet Lemmon is still inbound and brightening, passing nearest the Earth on October 21 and nearest the Sun on November 8.
© Victor Sabet & Julien De Winter — used with the credit NASA publishes
2024
The Magnificent Tail of Comet McNaught
Comet McNaught, the Great Comet of 2007, grew a spectacularly long and filamentary tail. The magnificent tail spread across the sky and was visible for several days to Southern Hemisphere observers just after sunset. The amazing ion tail showed its greatest extent on long-duration, wide-angle camera exposures. During some times, just the tail itself was visible just above the horizon for many northern observers as well. Comet C/2006 P1 (McNaught), estimated to have attained a peak brightness of magnitude -5 (minus five), was caught by the comet's discoverer in the featured image just after sunset in January 2007 from Siding Spring Observatory in Australia. Comet McNaught, the brightest comet in decades, then faded as it moved further into southern skies and away from the Sun and Earth. Over the next month, Comet Tsuchinshan–ATLAS, a candidate for the Great Comet of 2024, should display its most spectacular tails visible from the Earth.
© Robert H. McNaught — used with the credit NASA publishes
2023
Edwin Hubble Discovers the Universe
How big is our universe? This question, among others, was debated by two leading astronomers in 1920 in what has since become known as astronomy's Great Debate. Many astronomers then believed that our Milky Way Galaxy was the entire universe. Many others, though, believed that our galaxy was just one of many. In the Great Debate, each argument was detailed, but no consensus was reached. The answer came over three years later with the detected variation of single spot in the Andromeda Nebula, as shown on the original glass discovery plate digitally reproduced here. When Edwin Hubble compared images, he noticed that this spot varied, and on October 6, 1923 wrote "VAR!" on the plate. The best explanation, Hubble knew, was that this spot was the image of a variable star that was very far away. So M31 was really the Andromeda Galaxy -- a galaxy possibly similar to our own. Annotated 100 years ago, the featured image may not be pretty, but the variable spot on it opened a window through which humanity gazed knowingly, for the first time, into a surprisingly vast cosmos.
© Carnegie Institution for Science — used with the credit NASA publishes
2022
NGC 4631: The Whale Galaxy
NGC 4631 is a big beautiful spiral galaxy. Seen edge-on, it lies only 25 million light-years away in the well-trained northern constellation Canes Venatici. The galaxy's slightly distorted wedge shape suggests to some a cosmic herring and to others its popular moniker, The Whale Galaxy. Either way, it is similar in size to our own Milky Way. In this sharp color image, the galaxy's yellowish core, dark dust clouds, bright blue star clusters, and red star forming regions are easy to spot. A companion galaxy, the small elliptical NGC 4627 is just above the Whale Galaxy. Faint star streams seen in deep images are the remnants of small companion galaxies disrupted by repeated encounters with the Whale in the distant past. The Whale Galaxy is also known to have spouted a halo of hot gas glowing in X-rays.
© Michael Sherick — used with the credit NASA publishes
2021
M43: Streams of Orion
Where do the dark streams of dust in the Orion Nebula originate? This part of the Orion Molecular Cloud Complex, M43, is the often imaged but rarely mentioned neighbor of the more famous M42. M42, seen in part to the upper right, includes many bright stars from the Trapezium star cluster. M43 is itself a star forming region that displays intricately-laced streams of dark dust -- although it is really composed mostly of glowing hydrogen gas. The entire Orion field is located about 1600 light years away. Opaque to visible light, the picturesque dark dust is created in the outer atmosphere of massive cool stars and expelled by strong outer winds of protons and electrons.
© Jari Saukkonen — used with the credit NASA publishes
What happened on October 6
1915
World War I: Combined Austro-Hungarian and German Central Powers, reinforced by the recently joined Bulgaria launched a new offensive against Serbia under command of August von Mackensen.
World War I ↗
1990
Space Shuttle Discovery is launched on STS-41, and deploys the Ulysses space probe to study the Sun's polar regions.
Space Shuttle Discovery ↗
1995
Astronomers Michel Mayor and Didier Queloz reported the discovery of a planet orbiting 51 Pegasi (depicted) as the first known exoplanet around a main-sequence star.
Michel Mayor ↗
2008
The MESSENGER probe discovered Mercury's Rembrandt (pictured) – the second largest impact crater on the planet.
MESSENGER ↗
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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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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