THE Cosmic Keyhole, or by the government name of NGC 1999, is a reflection nebula in the Orion constellation. Located near the Orion Nebula, in a region of the Milky Way where stars are actively being formed, NGC 1999 is ~1350ly from Earth and is the composition of young star’s (V380 Orionis) formation discards.

UNLIKE emission nebulae, which alone emit light due to radiation ionization involving stars’ ultraviolet rays and nebula’s hydrogen atoms, NGC 1999 can’t shine unless a fixed light source illuminates the nebula due to its reflective type. The Cosmic Keyhole, however, is brightened by V380 Orionis (the light diffracting in the image above), a T Tauri star that sits covered by the smog of its birth.

REGARDING the “keyhole,” astronomers initially thought the hole was a Bok globule, a dense molecular cloud of gas and cosmic dust that absorbs light. In 2009, further observations were conducted using the Herschel Space Observatory (an infrared telescope that can penetrate dense material such as in this case), with supporting analyses from the Atacama Pathfinder Experiment, Nicholas U. Mayall Telescope, and the Magellan telescopes, debunking the Bok globule belief—instead concluding that NGC 1999’s mark isn’t anything but empty space. To this day, it’s still unknown why NGC 1999 has its iconic hole, but experts speculate that its creation is from local, new stars’ jets of gas puncturing the nebula’s foggy wall.

THE nebula was first discovered in the late 18th century by astronomer siblings Sir William and Caroline Herschel. It was later listed as object 1999 in the New General Catalogue—hence its formal name. In 1999, shortly after Servicing Mission 3A, the WFPC2 observations captured the image above.

CAPTION SOURCES

Main article w/ picture: "Hubble Peers at Mysterious Cosmic ‘Keyhole’" (NASA).

ADS

| "Hier ist wahrhaftig ein Loch im Himmel. The NGC 1999 dark globule is not a globule"

A&A

| "Herschel: the first science highlights"

CfA

| "Bok Globules"

ESA/Hubble

| "Cosmic Keyhole"

NASA

| "The Reflection Nebula in Orion"

| "NGC 1999"

| "Hubble's Nebulae"

| "Hubble Images Bok Globules"

(Caption written by @kaitropoli (me) using information from the sources above. Astronomy--knowledge of the universe, its population, fundamentals, and how everything is *known* to operate--is expanding every day with new things being discovered; the information listed could expire, so note that what I've gathered spans from 1990-2010 (with particular articles from the 2020s affirming up-to-date information with unchanged data).)