Starship Asterisk*

Zodiacal Light Panorama

Explanation: Sweeping from the eastern to western horizon, this 360 degree panorama follows the band of zodiacal light along the solar system's ecliptic plane. Dust scattering sunlight produces the faint zodiacal glow that spans this fundamental coordinate plane of the celestial sphere, corresponding to the apparent yearly path of the Sun through the sky and the plane of Earth's orbit. The fascinating panorama is a mosaic of images taken from dusk to dawn over the course of a single night at two different locations on Mauna Kea. The lights of Hilo, Hawaii are on the eastern (left) horizon, with the Subaru and twin Keck telescope structures near the western horizon. On that well chosen moonless night, Venus was shining as the morning star just above the eastern horizon, and Saturn was close to opposition. In fact, Saturn is seen immersed in a brightening of the zodiacal band known as the gegenschein. The gegenschein also lies near 180 degrees in elongation or angular distance from the Sun along the ecliptic. In the mosaic projection, the plane of our Milky Way Galaxy runs at an angle, crossing the horizontal band of zodiacal light above the two horizons. Nebulae, stars, and dust clouds of the bulging galactic center are rising in the east.

<< Previous APOD

Discuss Any APOD

Next APOD >>

[/b]

I love APODs like these that include a scale—in this case, degrees of elongation from the Sun—
but including both horizons (tricking one into thinking this a mere 180° panorama) also makes
my head hurt. I guess that's good too...

Sam

I agree, and this is a seldom-seen perspective very well executed. I'm not fully understanding it though, how can this be taken from dusk to dawn? - the sky will be constantly changing.

I have one question. I notice that the horizon on the left of the image is slanted at about 50 deg from the axes, but on the right side the horizon is almost vertical. What causes this change?

As I understand it, there were a series of pictures taken of the sky throughout the night. The camera angle was changed as the Earth rotated. I suspect that the answer involves the fact that the Earth is a sphere, and that the rotation of Earth is not in the same plane as the ecliptic, i.e. the zodiacal light that the image is tracing. The other comment was that the camera location was changed. In theory that could cause it, but I would expect the photographer to attempt to align the camera appropriately, and regardless, that should be absorbed when the images are stitched together for the panorama. Camera alignment might effect the shape of the image edges, but not the alignment of image components to each other.

Can anyone explain better?

FYI - the Discussion link on today's APOD takes you to yesterday's discussion.

Thanks; I've let TPTB know.

Irishman wrote:I have one question. I notice that the horizon on the left of the image is slanted at about 50 deg from the axes, but on the right side the horizon is almost vertical. What causes this change?

As I understand it, there were a series of pictures taken of the sky throughout the night. The camera angle was changed as the Earth rotated. I suspect that the answer involves the fact that the Earth is a sphere, and that the rotation of Earth is not in the same plane as the ecliptic, i.e. the zodiacal light that the image is tracing. The other comment was that the camera location was changed. In theory that could cause it, but I would expect the photographer to attempt to align the camera appropriately, and regardless, that should be absorbed when the images are stitched together for the panorama. Camera alignment might effect the shape of the image edges, but not the alignment of image components to each other.

Can anyone explain better?

In Hawaii on or around the night of April 3, 2011, the ecliptic plane in the west after sunset (on the right) comes straight up from the horizon and passess overhead. Later, before sunrise, however, the ecliptic meets the eastern horizon at the 50° angle you mentioned. The camera location change has nothing to do with the angle the ecliptic meets the horizon; the same angle would appear if the camera wasn't moved at all.

What makes this picture hard to comprehend are indeed the horizons: as your eyes move from right horizon to left horizon, you're also moving forward in time (later in the night). This is a 4D image projected onto two dimensions! Take out the horizons, however, and you just have a simple 360° wrap-around panorama which could have been taken from space.

--
Sam

I like this image. It shows a lot. You see the zodiacal light and gegenschein clearly, the dust on the plane of the ecliptic. It shows how the ecliptic goes through the centre of the galaxy, although I don't think it's evidence that the world will explode. I just believe that the spin of the solar system is slowly trying to match the spin of the galaxy.

Also in the Southern hemisphere (or anywhere you can see Scorpius and Sagittarius) you can see the galaxy clearly in the sky and it's as good as one of these photographs, but with the naked eye.

CCD cameras killed astronomy the same way that

http://www.youtube.com/watch?v=hiJ9AnNz47Y

ta152h0 wrote:CCD cameras killed astronomy the same way that

http://www.youtube.com/watch?v=hiJ9AnNz47Y

I don't understand.

MTV killed the radio star is a song describing the introduction of music videos and predicted the demise of radio, which didn't happen. CCD cameras were predicted to destroy astronomy " as we know it " and that didn't happen.

ta152h0 wrote:MTV killed the radio star is a song describing the introduction of music videos and predicted the demise of radio, which didn't happen. CCD cameras were predicted to destroy astronomy " as we know it " and that didn't happen.

I see. Well... actually, I don't, because I don't ever recall hearing a prediction that CCDs would destroy astronomy.

Astronomy magazine reported the sale of telescopes would plummet once ccd cameras were made available to trhe general public at affordable prices. Sky and Telescope echoed the sentiment. It was about 30 years or so ago. I thought todays APOD laid that claim to rest, forever.

JeremyExelby wrote:I agree, and this is a seldom-seen perspective very well executed. I'm not fully understanding it though, how can this be taken from dusk to dawn? - the sky will be constantly changing.

Jeremy, the technique is a digital mosaic. They take several images and then combine them with software. The images are aligned so the sky features align properly, so the image is continuous. Things like clouds or birds or whatnot are transitory and don't show up in the long exposures.

Sam, thanks for the reply. So it is a feature of the fact that axis of Earth's rotation is not aligned with the ecliptic. The ground changes angle with the sky.