M17, the glorious diffuse nebula with too many names (YC Astrophotography)

M17, the glorious diffuse nebula with too many names

This is Messier 17 (M17), the glorious diffuse nebula with too many names, located about 5000 – 6000 light-years away in the constellation of Sagittarius.

The characteristic shape of M17 was created by two separate objects that merged some time ago. The reddish colour comes from hydrogen gas clouds that are being excited by extremely hot newborn stars.

In 1833 John Herschel sketched and compared M17 to the capital Greek letter Omega with a long tail and he used the descriptive names Omega and horseshoe interchangeably. Although the shape of M17 doesn't conjure up an Omega or horseshoe for most modern day observers, the names Omega Nebula and Horseshoe Nebula are still widely used.

Since the brightest portions look like a vaporous checkmark, M17 also goes by the name of the Checkmark Nebula. If you turn your head upside down, you can see why observers in the Southern Hemisphere call it the Lobster Nebula.

M17 is also famously known as the Swan Nebula because of the illusion of a swimming swan surrounded by a wake. Hhumm, do you also see the number 2?

Please note: The following tables are updated every 24 hours.

Distribution of astrophotographers

This table shows the number of distinct astrophotographers who have been assigned and IOTD/TP award compared to the total number of images awarded.
	Distinct awarded users	Total awarded images
Image of the day
Top picks
Top pick nominations

Distribution of subject types

This table shows the distribution of awards per subject type, compared to the popularity of images of that subject type.
	Image of the day	Top pick	Top pick nominations	Total submitted
Deep sky
Solar system
Extremely wide field
Star trails
Northern lights
Noctilucent clouds
Landscape

Distribution of data sources

This table shows the distribution of awards per data source, compared to the popularity of images acquired from that data source.
	Image of the day	Top pick	Top pick nominations	Total submitted
Backyard
Traveller
Own remote observatory
Amateur hosting facility
Public amaeteur data
Professional, scientific grade data
Mix of multiple sources
Other
Unknown

The “AstroBin Image of the Day and Top Picks”, or IOTD/TP, is a long-running system to promote beautiful, interesting, peculiar, or otherwise amazing astrophotographs, with a focus on technical excellence. Learn more.

Submitted The date and time when you submitted this image for IOTD/TP consideration.	...
Views by Submitters (available since September 19th, 2023) Every image is assigned to 50% of available Submitters. In the event that at least 80% of them don't view the image before its time in the IOTD/TP process expires, it's assigned to the other 50% of Submitters and the process begins anew.
Promotions by Submitters When 3 distinct Submitters promote the image, it moves on to the next stage of the process: evaluation for Top Pick status. This requirement, in addition to anonymization of images and distribution to only a subset of them, prevents biases and ensures that the best images are selected.
Promotions by Reviewers When 3 distinct Reviewers promote the image, it moves on to the next stage of the process: evaluation for IOTD status.
Early dismissal Staff members have a lot of images to inspect on a daily basis, and they can dismiss images if they believe they don't meet the requirements for IOTD/TP selection. If an image is dismissed 5 times, it's removed from the process. This streamlines the process and ensures that any bias present in promotions could be overruled by other staff members.

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