page_title: NGC 2261
hierarchical_section_title: NGC 2261
caption_attribution_description: This is a reprocessing of one of the older Hubble Heritage releases. I believe that when it was originally processed that the individuals responsible did the best they could with the tools they had. Better software and faster computing allow me to improve significantly upon the original, which was created in 1999. This object lies along the Milky Way's dusty plane in the constellation Monoceros. One of my favorite things about this kind of nebula is that it reminds us that there can be a lot unseen in space. An optical illusion is produced by human intuition: it may look to you as though this is a bright cloud against a dark surface. In reality, this is a small hole in a largely unseen cloud which allows for light from a newly forming star to shine through. The variation in the nebula is most likely caused by shadows being cast by blobs of dust accreting near the young star. Note that the accretion process and the star itself are impossible to see in this image, and they occur at a scale too small and too distant for Hubble to see in any detail. The presence of the dusty knots and their close proximity to the star can be inferred by the shadows they cast and how fast they move across the nebula. Because the nebula is around a light year in size, the shadows appear to flow outward, which demonstrates to us the speed of light (or the speed of darkness?) in a way that I find profoundly beautiful. Wouldn't it be wonderful if the telescope could observe this object many more times so we could watch the light flow lazily through the Universe? I found a ground-based animation of the nebula's variation here: www.umanitoba.ca/faculties/science/astronomy/cbrown/imagi... Some more information and the original news release is here: hubblesite.org/image/904/news_release/1999-35 An APOD is here: apod.nasa.gov/apod/ap991020.html Data collected for Proposal 5574 made this image possible. WF/PC2 Cycle 4: Polarization Proposal Red: F814W;POLQ Green: F675W;POLQ Blue: F555W;POLQ North is 120° clockwise from up.
context_page_description: NGC 2261 is a variable nebula located in the constellation Monoceros. The nebula is illuminated by the star R Monocerotis, which is not directly visible itself.
context_section_description: NGC 2261 (also known as Hubble's Variable Nebula or Caldwell 46) is a variable nebula located in the constellation Monoceros. The nebula is illuminated by the star R Monocerotis (R Mon), which is not directly visible itself.
caption: An image of NGC 2261 by the Hubble Space Telescope
  Credit: HST/NASA/JPL/Judy Schmidt
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