Starship Asterisk*

Hello Ann! You get the distance in parsecs by dividing 1000 with the parallax in mas; and in light years by multiplying with 3.261. But for you, below are the values, of course using color to group results. StarDistances.png I looked up the parallax for 9 Sagittarii on English Wikipedia: 0.49 ± 0.40...

Mark Holm: The APOD image for March 17, 2021 is identified as being a cleaned up version of one of the images from Venera 13. I think it may actually be from Venera 14. Yes, judging by photos on David P. Mitchell's page http://mentallandscape.com/C_CatalogVenus.htm the image shows the Venera 14 land...

I don't get it: "Red sodium light"? Neutral sodium is famous for the doublet D Fraunhofer lines at 589.00 and 589.59 nm. But those have a distinct yellow color. The link given also identifies the sodium tail light with a wavelength of 5890 "angstroms". I know of no bright red sod...

Inspection of the image on pixel-level shows 1) light from bright stars is visible through the yellow beams 2) the lower end of the beams display a white core not visible at the top 3) the beams have not quite the same diameter If the beams were faked I would not expect to see these effects. Perhaps...

Yes, of course, Ann, you must be right, its a filter effect! Thank you, Color Commentator. As to the short yellow streaks, I think they are due to cosmic rays just as the very short streaks, perhaps coming in at a low angle. Asteroids at the same distance would create streaks of about the same lengt...

According to the link given (https://hubblesite.org/image/616/category/39-asteroids) they "were created by cosmic rays, energetic subatomic particles that struck the camera's detector". But I don't understand why some are colored yellow and others blue.

I like coffee. And I like tea. But I do not like them mixed together.

A stunning picture indeed. I reminds me of two rules-of-thumb for locating the position of the celestial south pole when looking at the sky: 2) Together with the LMC and the SMC it forms approximately an equilateral spherical triangle. This can be seen on alter-ego's image, although projection defor...

I wish NASA would post more realistic illustration... the composition of the Venus atmosphere as well as the atmospheric pressure (~90bar) at the surface are unlikely to ever allow such a view as depicted in this illustration. Science education is important, even when communicating to the general p...

The white lines are the slits, each of which is aligned with a galaxy of interest. They appear white because they show the overexposed direct light of the target galaxy. They correspond to the physical location of the galaxy on the image plane. On the vertical axis they are positioned so they don't...

I also wondered about the allmost white spectra: If they are foreground stars, why include them? Further questions: The parallel horizontal arrangement of the spectra suggests that the positions of the spectra in the image are not correlated with the position of the galaxy in the sky, but then why a...

This does not require any math, a simple calculation will do: The Sun's luminosity is measured to be 3.826·10 26 W, so the Sun emits an energy of E = 3.826·10 26 J each second. Using E = m · c 2 (where c = 299792458 m/s is the speed of light) and a pocket calculator we get m = E / c 2 = 4.257·10 9 k...

The caption states "two mornings ago". Unfortunately such inprecise statements are common on APOD. Using "Starry Night" I find, that the image was taken on June 11 at around 3:00 GMT.

Using Starry Night I have identified some other objects: The relatively bright star above the mountail top is the orange giant Beta Ceti with magnitude m = 2.00. Starry Night uses the old name Deneb Kaitos, the standardized IAU name is Diphda. The reletively bright star at seven o'clock relative to ...

To the upper left one can see six regularly placed dots. I have tried to simulate the view with Starry Night software, but nothing showed up. What could it be?
Holger

The visit of New Horizons at Ultima Thule (still an unofficial name) to me brings up the question what one should call the objects in the Kuiper Belt. I do not like transneptunian objects (a description, not a name) or qubewanos :shock: . The Solar System contains planets , dwarf planets and minor p...

This is the best photo of supernumenary bows that I have ever seen. What strikes me is, that the distance between the bows seems to be larger higher up, so the bows do not form circles concentric with the primary rainbow. If correct, how can that be explained?

The caption says "The likely intruder galaxy is on the left". There are at least two magenta blobs to the left of the ring galaxy, so which one is it?
And how could it be identified, has it nearly the same redshift as the galaxy? Is this suggested by model calculations of the collision?

"...looking south toward Europe's highest peak...". Mont Blanc (4810 m) is not the highest peak in Europe. That distinction belongs to Mt. Elbrus in the Caucasus Mountains (5642 m). Quick question: In which European country lies the top of Mont Blanc? The answer might be the Netherlands, a...

Note the overexposed image of Mercury at about 10 o'clock drifting slowly to the left after superior conjunction with the Sun on October 25, 2003.

Nothing fancy is needed, "black cluster" would suffice.

Green is definitely a spectral color. If the eye receives photons with a wavelength around 530 nanometers, the brain registers this as "green". If the eye receives a mixture of blue and yellow light, the brain interpretes this as "green" as well, allthough no green photons have b...

This is one of the best composites of its kind. Well planned, beautifully put together. And luck with a clear sky.
Holger Nielsen

I think the photo shows a hybrid between an annular eclipse and a "beaded" eclipse. That is the name I would give to a solar eclipse, where sunlight would be visible at many positions around the solar limb, sifting through low-lying areas on the Moon. Such an eclipse would be neither annul...

"Gandalf" is standing at the bottom centre of the picture with his back to the viewer...