Starship Asterisk*

It would be so cool if the radio jets also had an optical Ha counterpart like the ones associated with M82. They sort of kind of do - there is a long and complex train of emission-line filaments and blobs along one edge of the northeastern jet. Here is a pseudocolor montage of H-alpha images, rotat...

How interesting! The Earth's atmosphere looks strangely reddish, with a thin layer of greenish-blue on top. In this nocturnal grazing view, we're seeing the airglow layers of O and Na excited by (IIRC) collisions with molecules (OH glows pretty fiercely at longer wavelengths; these are all sworn en...

No, it's not, The most distant objects known are at redshifts about z=7, which would be about 500 million years cosmic age. The highest-redshift galaxies known at this point which are clear spirals have redshifts about z=2.5 (and there are very few of those), which would be a cosmic age of 2.5 bill...

No, it's not, The most distant objects known are at redshifts about z=7, which would be about 500 million years cosmic age. The highest-redshift galaxies known at this point which are clear spirals have redshifts about z=2.5 (and there are very few of those), which would be a cosmic age of 2.5 billi...

I would like to know more detail about the UV data and what it's adding to the Ultra Deep Field image. The APOD post says the UV data helped study star formation in galaxies 5 to 10 billion LY away. I haven't done the math on it, but I would think that even energetic gamma rays associated with star...

of all the exoplanet solar systems we've discovered, is there any indication of some kind of regularity of how solar systems spin relative to the galactic plane? No. The fact that we see planets found both from transits and Doppler motions all over the sky says that, as well as you can tell from th...

On the discovery of gravitational lensing - the popular-level book The Sky at Einstein's Feet devoted 2 chapters to the discovery and exploitation of gravitational lensing. I think it's now print-on-demand, but most of it can be found from Google Books here . There were, as so often happens, a lot o...

Responding to a few questions that have come up - When galaxies pass close enough to exchange enough energy, they become bound even if they weren't before (although in today's Universe, statistics indicate that most interacting and merging galaxies were already in weakly bound pairs). The exchange c...

[ A really fun way to get to a more intuitive understanding of orbital dynamics is to read "The Smoke Ring" series by Larry Niven EDIT ** The first book is called "The Integral Trees" ** Niven's inimitable short form: East takes you Out, Out takes you West, West takes you In, In...

Nitpicker wrote: The galaxy is shaped like a prolate spheroid.

Or not. It shows a significant velocity gradient end-to-end, just like an S0 lenticular galaxy of that luminosity seen edge-on. If it's prolate, the shape has to be tumbling at this rate.

What ANGLE would another galaxy have to come in at to produce such a thing? Simulations show that such a structure is longer-lasting the more nearly the shredded former companion is to orbiting right over the poles of the main galaxy disk. This happens because of differential precession - just as w...

Even if moving more slowly when farther out, they're spread over a lot more volume (actually, for the same reasons stars in galaxies concentrate toward the center). The situation in many galaxies gives less bias than this, in fact - flat rotation velocity with radius, as often measured, reduces the ...

These searches all key not on the supermassive black hole, but the much larger and more massive region in the galactic center where the density of dark-matter particles would be highest. This gives a strong peak in the annihilation signal (always assuming that the particles are self-annihilating, kn...

jsanchezjr wrote:The poor guy never saw a single comet althougt the purpose of the catalog was precisely that.

Wikipedia says Messier discovered 13 comets.

Indeed. Experience has shown (tracked by, for example, the HST outreach staff) that artifacts such as cosmic rays, bleeding trails from saturated stars, and satellite trails can be enormously distracting for the impact of images on a broad public. Research articles are full of images marred by such ...

As noted, there are distant galaxies visible through NGC 5101. The one at about 7 o'clock appears face-on, and very similar to NGC 5101 itself. It even seems to have darker, more rarified streaks within it. So what I find interesting is that if we are looking through this distant one, we are peerin...

The reason why an 18,000 K blackbody is generally considered the most blue (and why most people see it that way) is that this is the temperature where you have the most "blue" (450 nm) energy in comparison with longer visual wavelengths. As you get hotter, the energy across the visual spe...

The very blue color of the central star testifies to its high temperature. How hot is it? I have no idea, but I would be surprised if it not at least, say, 40,000K. It could well be hotter. Above about 25,000 K, optical colors no longer give much information on stellar temperature - blackbody spect...

"Typical view of a nearly full moon", well, a little nit-picking, in this image it is correct for maybe Australia, with Mare Crisium at the lower left. :wink: Hemisphere chauvinist! Actually the whole image is shown with south at the top. SInce we see the far side of the disk of M31 to ou...

Wow - eighteen years! 1995 seems so long ago. I am humbled to see that images credited to me, taken with equipment ranging from HST down to a 35mm camera using actual film, have shown up over the years something like 50 times (many in the early days when there was not the stiff and skilled "ama...

We've come a long way! This reminded me of perhaps our first UV view of the Large Magellanic Cloud. It was provided back in 1972, when the Apollo 16 crew briefly operated our first observatory on the surface of another world. Built by George Carruthers of the Naval Research Lab, the S201 camera was ...

Another catalogue that I've been unable to discover is the one that gives several objects in the LMC the 'name' DEM L followed by a number. I've web searched and found this article that studies them ,but it gives no clue about who or what gave rise to the DEM acronym . Got it: the source for the DE...

The Explanation contains "...Milky Way Galaxy has absorbed several smaller galaxies..." however, the referenced http://apod.nasa.gov/apod/ap080619.html states that the evidence "supports the cosmological scenario...." It is not necessarily a fact that our galaxy has absorbed sev...

I wonder if any GRBs have been or could be seen with the naked eye ? You'd have to be looking at the right place at the right time - pure chance - and most people likely wouldn't know what they're seeing. Still, the thought that one might see light that is billions of years old, without a telescope...