APOD: A Spectre in the Eastern Veil (2013 Oct 30)

[APOD Robot]

A Spectre in the Eastern Veil

Explanation: Frightening forms and scary faces are a mark of the Halloween season. They also haunt this cosmic close-up of the eastern Veil Nebula. The Veil Nebula itself is a large supernova remnant, the expanding debris cloud from the death explosion of a massive star. While the Veil is roughly circular in shape covering nearly 3 degrees on the sky in the constellation Cygnus, this portion of the eastern Veil spans only 1/2 degree, about the apparent size of the Moon. That translates to 12 light-years at the Veil's reassuring estimated distance of 1,400 light-years from planet Earth. In the composite of image data recorded through narrow band filters, emission from hydrogen atoms in the remnant is shown in red with strong emission from oxygen atoms in blue-green hues. In the western part of the Veil lies another seasonal apparition, the Witch's Broom.

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[Boomer12k]

You can even see a "bat face" in the upper center part...

:---[===] *

[Beyond]

BOO!!

[STERNDALE]

It appears to be "The Ghost Owl Nebula" Hoo! Hoo! Happy Halloween!

[yasgur]

To me this looks like an actual picture than most formations I've seen with descriptive names. And yes, an owl for sure.

[orin stepanek]

It's that time of year!

Click to view full size image

Brown Lady of Raynham Hall, a claimed ghost photograph by Captain Hubert C. Provand. First published in Country Life magazine, 1936

[bearkite]

Speaking of seeing faces and things in astronomical objects...

I can't look at this one and not think of the time I viewed this through John Voghts 32 (?) up at Cherry Springs and saw the "Mule Head Nebula" for the first time. (hint -- rotate the image)

Happy Halloween all...

Heeee Haaaaaaaw

[Ann]

This is supposedly a picture of fairies, taken by Elsie Wright in 1917, and promoted by Sherlock Holmes creator Arthur Conan Doyle as genuine.

For some reason, I think fairies and ghosts and spectres and what not are a lot more fun when you just relax and accept them as make believe.

Hey... that is a fun spectre in the Veil Nebula. What should we call it, Li'l Veily Ghost?

Ann

[DeeBee]

This nebula should be renamed The Owl Nebula. We see a perfect image of the entire nebula as an owl in flight with both wings stretched out!

[geckzilla]

There's already a nebula called the Owl Nebula, though. It looks like an owl's face. http://en.wikipedia.org/wiki/Owl_Nebula

[CharliePatriot]

Need some help here. Exactly what distance is denoted by "Light Year".? Have heard several and don't now which is true.

[BMAONE23]

Need some help here. Exactly what distance is denoted by "Light Year".? Have heard several and don't now which is true.

It is the distance that light travels in one year
186,000 MPS
11,160,000 MPM
669.600.000 MPH
16,070,400,000 MPD
5,865,696,000,000 MPY
5 Trillion 865 Billion 696 Million miles per Light Year

Or 244,404,000 times around the earth

[BMAONE23]

At first glance I thought of this cute little guy

[ta152h0]

My departed 69 Torino Cobra Jet did that, called pinging here on Earth.

[Chris Peterson]

Need some help here. Exactly what distance is denoted by "Light Year".? Have heard several and don't now which is true.

It is the distance that light travels in one year
186,000 MPS
11,160,000 MPM
669.600.000 MPH
16,070,400,000 MPD
5,865,696,000,000 MPY
5 Trillion 865 Billion 696 Million miles per Light Year

Or 244,404,000 times around the earth

Or in civilized units that the rest of the world understands, one light year is

9 454 254 955 500 kilometers
0.306 391 545 86 parsecs

[geckzilla]

Need some help here. Exactly what distance is denoted by "Light Year".? Have heard several and don't now which is true.

It is the distance that light travels in one year

Through a vacuum. An important but often neglected variable.

[ta152h0]

anybody measured speed of light when not in vacuum ?

[Chris Peterson]

anybody measured speed of light when not in vacuum ?

Sure. Many of the early attempts to measure the speed of light were conducted in Earth's atmosphere (and even those that were astronomically based required part of the light path to be in the atmosphere). Experiments involving Cherenkov radiation require measuring the speed of light in different mediums. And practical optics also involves measuring the speed of light in optical materials, as this is critical to making practical use of refraction.

[neufer]

anybody measured speed of light when not in vacuum ?

[b][color=#0000FF][size=150]Fizeau interferometer for measuring the effect of water movement upon the speed of light[/size][/color][/b]

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<<The Fizeau experiment was carried out by Hippolyte Fizeau in 1851 to measure the relative speeds of light in moving water. Fizeau used a special interferometer arrangement to measure the effect of movement of a medium upon the speed of light.

According to the theories prevailing at the time, light traveling through a moving medium would be dragged along by the medium, so that the measured speed of the light would be a simple sum of its speed through the medium plus the speed of the medium. Fizeau indeed detected a dragging effect, but the magnitude of the effect that he observed was far lower than expected. His results seemingly supported the partial aether-drag hypothesis of Fresnel, a situation that was disconcerting to most physicists. Over half a century passed before a satisfactory explanation of Fizeau's unexpected measurement was developed with the advent of Albert Einstein's theory of special relativity. Einstein later pointed out the importance of the experiment for special relativity.>>

[Anthony Barreiro]

Need some help here. Exactly what distance is denoted by "Light Year".? Have heard several and don't now which is true.

It is the distance that light travels in one year
186,000 MPS
11,160,000 MPM
669.600.000 MPH
16,070,400,000 MPD
5,865,696,000,000 MPY
5 Trillion 865 Billion 696 Million miles per Light Year

Or 244,404,000 times around the earth

Or in civilized units that the rest of the world understands, one light year is

9 454 254 955 500 kilometers
0.306 391 545 86 parsecs

I find it helpful to consider how long light takes to travel from familiar objects to us here on Earth. Light reflected off the surface of the Moon takes less than a second and a half to get to the surface of the Earth. Light from the Sun takes about eight and a half minutes to get to Earth. Light reflected from Jupiter takes about 40 minutes to get to Earth. Light reflected from Neptune takes about four hours to get to Earth. Light from the nearest star, Alpha Centauri (or Proxima Centauri if you want to quibble), takes four years to get to our solar system. These landmarks give me a basis for better understanding a nebula that is ten light years across and 1400 light years away from us, for instance.

[Nitpicker]

Need some help here. Exactly what distance is denoted by "Light Year".? Have heard several and don't now which is true.

It is the distance that light travels in one year

Through a vacuum. An important but often neglected variable.

Well, if we're getting technical, it is the distance that light travels in a vacuum in one Julian year (365.25 days [86,400 SI seconds per day]).

Or in civilized units that the rest of the world understands, one light year is
9 454 254 955 500 kilometers

Not that we're that civilised, nor civilized, but the rest of us know them as kilometres. (Picky, picky.)

For a unit that is truly civilised, militarised, internationalised and also rather natural to planet Earth, there is the nautical mile:
http://en.wikipedia.org/wiki/Nautical_mile
"The nautical mile (symbol M, NM or nmi) is a unit of length that is about one minute of arc of latitude measured along any meridian, or about one minute of arc of longitude at the equator (both at sea level). By international agreement it has been set at 1,852 metres exactly (about 6,076 feet)."

But I digress. Like kilometres, nautical miles are not much chop for astronomy (and statute miles can take a hike too -- they're not bad for hiking). The more convenient light years and astronomical units, both have exact definitions in units of the SI metre (which is itself defined relative to the speed of light in a vacuum). And the (pretty nifty) parsec is defined exactly as 648000/π astronomical units.

[Nitpicker]

Through a vacuum. An important but often neglected variable.

Well, if we're getting technical, it is the distance that light travels in a vacuum in one Julian year (365.25 days [86,400 SI seconds per day]).

Oops, looks like I nitpicked the wrong person. I've been demoted to an up-arrow.

[geckzilla]

Your title is your username until further notice. Lack of imagination on my part.

[KarenG958]

Does this remind anyone else of the Id monster in Forbidden Planet?

[neufer]

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Does this remind anyone else of
the Id monster in Forbidden Planet?

Id sorta does.