Starship Asterisk*

Meteor spectroscopy is indeed done. It takes patience or a lot of automation, since the equipment has to be capable of grabbing the data at any time and very quickly. This means that a diffraction grating or prism is added to a wide-angle system, and take the occasional set of data when a meteor bri...

I remember learning that they wanted to put more of the nested mirrors but couldn't because of weight restrictions. Still an amazing instrument! At the field center, the mirror assembly delivers sharper images than any of the Chandra detectors can take full advantage of (tricks like subpixel recons...

Why the gap in the data? Chandra's much-used ACIS instrument has 8 CCD detectors of two different kinds in adjacent arrays, one 2x2 square and one 4x1 optimized for dispersed spectra; each CCD covers a region about 8 arc minutes square. The break in the light echo in the released image composite is...

Shortly after sunset, would the vanishing point be in the sky? Anyone got pics? Closest I can come is this 1981 shot of the shadow of Mt. Lemmon, Arizona, being cast on the open atmosphere just before sunrise. The summit altitude (close to 3000 meters) give the rising sun enough dip below the usual...

I read through yesterday's comments, and didn't find an answer: Since both the Charon and Pluto photographs are shot pretty much face-on (sunward facing), I presume New Horizons must have passed by on a trajectory radially outwards from the inner solar system, but almost aimed directly AT Pluto et ...

Yeah, what Ann said. On top of that, the level of ionization in certain parts of the Magellanic Stream (cold hydrogen pulled from the Magellanic Clouds), and the so-called Fermi Bubbles seen in X-rays and gamma rays, fit with the idea that the Milky Way's nucleus underwent an active episode somethin...

In H-alpha, the most striking feature of M94 is a tight ring of H II regions just at the boundary where the surface brightness of spiral structure changes. Here is an old continuum-subtracted) image in pseudo color: M94VCVHa2.jpg (Historical "grumpy old astronomer" note - I'm pretty sure t...

Wow, APOD got this really fast! Indeed, the clouds are pretty green. The [O III] lines are by far the strongest in the optical range, outshining even H-alpha by 3x or more. Their spectra (not coincidentally) look almost identical to that of Hanny's Voorwerp: http://astronomy.ua.edu/keel/research/WHT...

[ In today's APOD, why does the dark portion of the moon get darker as one approaches the terminator ? You need to consider how to make an image like this. The dynamic range of the actual Earthshine lit Moon is much to wide to display on a monitor in a linear fashion. Indeed, it is too wide to effec...

The fastest way to assess Hubble data is almost always the Hubble Legacy Archive. Entering Pal 12 as the target shows two series of images, 26 July 2003 and 21 May 2006. Both used the Advanced Camera for Surveys.

Would someone enlighten me as to how, over a span of a few years, there can be "measured motion"? I've been told before (here) that even close stars like those of Orion, would not have any apparent movt relative to one another in a single human's lifetime. So how can there be anything mea...

I have a question about the image. The three large and highly visible stars to the left and lower of the spiral galaxy, each have four reflective rays emanating from them. What causes those rays to be multi-colored? Is that caused by the light of the stars passing thru different gases and do all st...

The timing on this one was great - in class today I was talking about how disk galaxies and ellipticals produce different kinds of tidal debris, because the stars in the disk (and gas clouds in the disk) share very nearly the same velocity at a given point. (Put this APOD up on a big screen and turn...

Here's a pseudocolor green-light closeup of the northeast "dogleg" feature, from an old Cerro Tololo data set. They are kind of blue (we measured B-V=0.4). The concentration in the middle had us also thinking tidal tails, albeit viewed at a suspicious angle (especially to have four of them...

Markus Schwarz wrote:What is the "object" below the Magellanic Clouds? It appears to be in front of the (water) clouds, so it must be something terrestrial?

It's in the right place to be Canopus, which is plenty bright, if its light is scattered into a blur by the foreground clouds.

The first (widely-reproduced, at any rate) color pictures of deep-sky objects came from the work of photo expert William Miller with several of the scientists at Mt. Wilson at Palomar in the late 1950s, rating an article in Life magazine. In the 1960s, some of the astronomers up the coast at Lick Ob...

There is a file of daily sunspot numbers (a visual average with groups counting more) here. From 1973-1975, the highest peak (comparable to recent numbers) is at 1973.68, followed pretty closely by 1974.77 and 1975.59. The middle one fits your date range (would be about May 17, 1974).

Hydrogen doesn't want to stay around on any of the inner rocky worlds in our solar system. There is a similar photograph of the Earth in the UV wavelength of hydrogen's Lyman alpha emission taken from the lunar surface during Apollo 16, using George Carruthers' UV telescope: http://science.nasa.gov/...

Next time you are on an airplane, if the sun is above the plane; let's say from 10 am to 2 pm position, you can look down at where the shadow of the plane would be and you'll see the same phenomenon reflected on the ground, of course the shape of the person is replaced by the shape of the plane. It...

starsurfer wrote: I imagine Ha would show a lot more!

Indeed. I once did this narrowband image (not particularly cleaned up yet) for some filter tests, bringing out hundreds of emission regions.

I'm pretty sure individual stars show up in a few places, although you'd need independent data to be sure which ones are single stars and which are clusters. I have an image of NGC 206 (the bright star cloud almost due left of M31's core in the APOD), the area where Hubble found Cepheids in the famo...

NC 253 does look more organized elsewhere in the spectrum. Going into the infrared, it has a pretty prominent two-armed pattern, with a bar and probably an inner ring - shown, for example, in Spitzer data : http://www.spitzer.caltech.edu/uploaded_files/graphics/fullscreen_graphics/0009/6338/ssc2013-...

Joules wrote:Center of rotation/mass is within or near the neck.

Im not sure we know that from this image series. They may have been arbitrarily recentered for display at a central position.

I can't think of any reason that a central BH has to be aligned with its rotation axis normal to the galactic plane. In fact, the statistics of radio jets in Seyfert galaxies (mostly spirals,whose radio jets are seldom more than a few thousand light-years in length) are consistent with the axis of ...

There may be a background cluster of galaxies south of the small galaxy remnant - one of the blue objects is the quasar 3C 275.1 at z=0.55. An SDSS finding chart centered on the quasar is here . Some of those galaxies look about the right color and magnitude to be in a cluster around the quasar. Pok...