Visibility of celestial bodies during the daytime

[cptolemy]

TL;DR Summary

comet/asteroid/planet/star visibility during daytime

Good afternoon,

I was wondering if someone can point me out a study or perhaps a solution, to know with some assurance if a body with a certain magnitude (m) rising before the sun with a certain angular separation (a) can or cannot been seen with the naked eye.

It's the heliacal phenomenon I believe. Suppose a star with an apparent magnitude of -2 rising 30 degrees apart (and before) the sun (mag. aprox. -26). Will it be seen by us all day long, or just at sunrise? Or not at all?

I believe that perhaps a formula must exist for calculating this visibility.

Clear skies

CPtolemy

PS - merry christmas to all :)

 

[sysprog]

You can read about such visibility and download associated software at:
http://www.alcyone-ephemeris.info/planetary_lunar_and_stellar_visibility.html

 

[cptolemy]

Hi

Thank you. But I have that software (actually all the Alcyone software, free and paid - it's great). But it does not allow (I think) asteroids or comets.

Clear skies,

 

[sysprog]

Hi

Thank you. But I have that software (actually all the Alcyone software, free and paid - it's great). But it does not allow (I think) asteroids or comets.

Clear skies,

A comet is an asteroid that got close enough to the sun to incandesce. You can't see other asteroids with the unaided eye. Only the 'great comets' are ever clearly visible without magnification. Such objects must be tracked in advance by telescopic observation for their unaided visibilities to be accurately predicted. The things that can legitimately be said regarding hypothetical visibilities within specific near-solar regions for specific temporal and locational ranges on Earth are not generable by simple formulae, but must be computed on a case-by case basis. You can read the Alcyone source code if you want to investigate the algorithmic basis that their software relies upon for predictions regarding larger objects.

 

[cptolemy]

Hi

Yes, you are right. I believe that the table used in Alcyone, that relates the magnitude with the arc is a good guess. For instance, for a body with an apparent magnitude of -1.5, the heliacal rising should happen with an arc of 8.4 degrees. But a body with an app. magnitude of 2.0, would require an arc of 13.3 degrees.
But it's well stated: "We do not know whether these values of the arcus visionis are correct; it is possible that the values for heliacal phenomena are slightly high and for acronychal phenomena slightly low."

Still, is a good reference - thanks :)

Clear skies.

 

[snorkack]

Remember that important parts are angles at which they rise.
The brightness of a star in clear air depends on its altitude/airmass. The brightness of sky depends both of location in sky and altitude of Sun - the only symmetry it has is bilateral one around direction to Sun. Am not sure there is a simple equation to express it.

 

[cptolemy]

Hi

Yes, there's not a simple equation. The table serves - however - as a basic reference of standards values in normal conditions. To know for sure, and accuratly, would involve many calculations and variables.
But it gives a general idea - which is good.

Clear skies and... merry Christmas.

 

[davenn]

A comet is an asteroid that got close enough to the sun to incandesce.

No, that's completely incorrect. They are, in general, very different things, most asteroids originate from within
the solar system, the asteroid belt between Mars and Jupiter plus a few rogues from elsewhere.
They are generally solid rock through to rocky iron through to solid irons.
Comets, on the other hand, originate from outside of the main part of the solar system, usually
the Kuiper Belt and a few rogues from elsewhere. Comet composition is usually more icy and dusty,
commonly referred to as dusty snowballs with only some being more solidDave

 

[davenn]

Summary:: comet/asteroid/planet/star visibility during daytime

Good afternoon,
......
It's the heliacal phenomenon I believe. Suppose a star with an apparent magnitude of -2 rising 30 degrees apart (and before) the sun (mag. aprox. -26). Will it be seen by us all day long, or just at sunrise? Or not at all?

Clear skies

CPtolemy

PS - merry christmas to all :)

Many of the brighter stars and planets can be seen in the eastern pre-dawn sky or the western
post sunset sky. Tho the stars will generally have a wider separation from the Sun.
Venus can but no stars can be seen naked eye during daylight hours ( sunrise to sunset)
I have heard some say that they have seen Jupiter in daylight hours, but I am skeptical.

 

[sysprog]

No, that's completely correct. They are, in general, very different things, most asteroids originate from within
the solar system, the asteroid belt between Mars and Jupiter plus a few rogues from elsewhere.
They are generally solid rock through to rocky iron through to solid irons.
Comets, on the other hand, originate from outside of the main part of the solar system, usually
the Kuiper Belt and a few rogues from elsewhere. Comet composition is usually more icy and dusty,
commonly referred to as dusty snowballs with only some being more solidDave

I assume you meant "incorrect". I agree with you regarding the distinctions between comets and asteroids; however, in my view, all comets are asteroids, while not all asteroids are comets. I see asteroids as a broader category of objects that includes comets.

I am not alone in expressing a view that is at least akin to that; e.g., from http://curious.astro.cornell.edu/our-solar-system/comets-meteors-and-asteroids:

Comets, meteors, and asteroids are often grouped together since they are all basically the same thing: small pieces of rock and/or ice that aren't part of a major planet.​

I acknowledge that the 'curious.' subdomain name suggests that the content is apt to be popularistic.

A more rigorous publication, 'Evolution of Comets Into Asteroids', by Paul R. Weissman of the Jet Propulsion Laboratory, and William F. Bottke Jr. and Harold F. Levison of the Southwest Research Institute, said something like what I said, but appears to me to follow up with something more in keeping with what you said: from https://www.boulder.swri.edu/~hal/PDF/asteroids3.pdf:

At present, the choice between a cometary versus an asteroidal designation for a newly discovered object is based on the presence or absence of visible coma. This has occasionally led to objects being classified as both types, in particular when coma was discovered long after the object had been catalogued as an asteroid. The most notable case is the Centaur asteroid 2060 Chiron, which is also known as comet 95P/Chiron. In addition, this scheme has led to Kuiper belt objects being numbered as asteroids, though their location in the solar system argues strongly for a significant icy fraction in their compositions. Since no formal definitions of comets and asteroids exist, we will use the following, slightly modified definitions from Paper 1.​

The definitions that follow therafter in that paper appear to me to be reasonably consistent with your comments.

 

[snorkack]

There is a bigger distinct problem with deciding twilight visibility of comets. Which is that comets are extended objects - nucleus, coma and tail.
Hale-Bopp nucleus was about 30...40 km across. Far bigger than the biggest Earth-crossing asteroids
Note, however, that when considering a close approach of a great comet, the orbital motion of the comet should be considered along with Earth rotation. For example, a comet with perihelion at 1 au and inclination 0 to ecliptic passing at Moon´ s distance from Earth would be moving 12 km/s and that makes a radian in 30 000 seconds... while Earth rotation is about a radian in 14 000 seconds. Inclination 180 to ecliptic would make relative speed 72 km/s, which in Moon´ s distance would be a radian in 5000 seconds!

 

[sysprog]

Many of the brighter stars and planets can be seen in the eastern pre-dawn sky or the western
post sunset sky. Tho the stars will generally have a wider separation from the Sun.
Venus can but no stars can be seen naked eye during daylight hours ( sunrise to sunset)
I have heard some say that they have seen Jupiter in daylight hours, but I am skeptical.

From: https://Earth'sky.org/astronomy-essentials/10-surprising-things-to-see-in-the-daytime-sky

​

Jupiter captured in 2012, during a close pass near the moon.​

Image by Dave Dickinson (@Astroguyz on Twitter) via Universe Today.​

​

5. The planet Jupiter. Even some seasoned astronomers are surprised to learn that mighty Jupiter can be glimpsed with the unaided eye in a sunlit sky. I don’t want to mislead you, as this isn’t an easy observation. Jupiter is significantly dimmer than Venus, and finding it takes a good bit more effort (not to mention exceptionally good eyesight and excellent atmospheric conditions).​

​

The best time to see Jupiter in daylight is when it’s near a “quadrature” when Jupiter is about 90 degrees away from the sun in the sky. This is similar to the arrangement of first quarter and last quarter moon. In fact, it is also very helpful to have a quarter moon nearby as a kind of sky landmark to guide you to Jupiter. Notice the quarter moon in the image above, for example.​

​

And, by the way, the reason you want the planet at quadrature – about 90 degrees from the sun – is that the sky is slightly darker there, due to a phenomenon known as polarization.​

​

 

[davenn]

Jupiter captured in 2012, during a close pass near the moon.Image by Dave Dickinson (@Astroguyz on Twitter) via Universe Today.

not applicable --- it's a photo, not a visual observation

 

[davenn]

I assume you meant "incorrect". I agree with you regarding the distinctions between comets and asteroids; however, in my view, all comets are asteroids, while not all asteroids are comets. I see asteroids as a broader category of objects that includes comets.

yeah incorrect
and no I would not agree with that definition

 

[davenn]

A more rigorous publication, 'Evolution of Comets Into Asteroids', by Paul R. Weissman of the Jet Propulsion Laboratory, and William F. Bottke Jr. and Harold F. Levison of the Southwest Research Institute, said something like what I said, but appears to me to follow up with something more in keeping with what you said: from https://www.boulder.swri.edu/~hal/PDF/asteroids3.pdf:

At present, the choice between a cometary versus an asteroidal designation for a newly discovered object is based on the presence or absence of visible coma. This has occasionally led to objects being classified as both types, in particular when coma was discovered long after the object had been catalogued as an asteroid. The most notable case is the Centaur asteroid 2060 Chiron, which is also known as comet 95P/Chiron. In addition, this scheme has led to Kuiper belt objects being numbered as asteroids, though their location in the solar system argues strongly for a significant icy fraction in their compositions. Since no formal definitions of comets and asteroids exist, we will use the following, slightly modified definitions from Paper 1.
The definitions that follow therafter in that paper appear to me to be reasonably consistent with your comments.

exactly

The biggest hassle I had with your description was ...

A comet is an asteroid that got close enough to the sun to incandesce.

this part is just rubbish. You will never see a tail/coma from an asteroid

 

[sysprog]

not applicable --- it's a photo, not a visual observation

OK, your credence; your rules. For my part, I've seen Jupiter as a tiny spicule just after dawn, on a day when the TV news had alerted us that it would be visible, along with where in the sky and the time interval. I think I didn't hallucinate it, and I think that Mr. Dickinson didn't fake the photo that he posted, and that even though it was taken with a camera lens, the photo adequately evinces the fact of the visibility to the unaided eye.

 

[sysprog]

exactly

The biggest hassle I had with your description was ...

A comet is an asteroid that got close enough to the sun to incandesce.

this part is just rubbish. You will never see a tail/coma from an asteroid

It was imprecise and as worded, misleading. Because there is no formal definition for the term 'asteroid', I take the view that, informally, all of the solar satellites which are not planets, planetoids, planet-orbiting, or planetoid-orbiting, may be called asteroids. For clarity on this forum, I should have said something like 'icy mass' instead of 'asteroid'.

 

[snorkack]

So, listing Great Comets...

1. 1744 - by 18th February, brighter than Venus; 1st of March, near perihelion at 0,2 au, could be seen in daytime by naked eye, estimated at -7
2. 1811 - magnitude 0, like Hale-Bopp did not get close to Sun or Earth
3. 1861 - perihelion at 0,82 au, but approached to 0,13 au of Earth, magnitude between 0 and -2
4. 1874 - magnitude 0 to +1
5. 1882 - transited Sun, reached magnitude -17 when grazing Sun, could be seen in daytime sky next to Sun
6. 1901 - magnitude -1,5
7. 1910 - magnitude -5 when at perihelion of 0,13 au, visible in daylight
8. Arend-Roland, 1957 - magnitude -1
9. Ikeya-Seki, 1962 - sungrazer, magnitude -10, visible in daytime next to Sun
10. West, 1976 - magnitude -3 at perihelion of 0,2 au, visible in daytime
11. Hyakutake, 1996 - passed 0,1 au from Earth, magnitude 0
12. Hale-Bopp, 1997 - magnitude -1, far from Sun or Earth
13. McNaught, 2007 - magnitude -5,5, perihelion at 0,17 au, visible in broad daylight
14. Lovejoy, 2011 - magnitude -3 to -4, too dim to see a sungrazer.

So... how to predict visibility of a sungrazer?

 

[sysprog]

Comet ISON was a sungrazer that was discovered on 09-21-2012. The linked wikipedia article is informative regarding how such discoveries are made. Its trip through the perihelion caused it to burn to inobservability even for space telescopes, so it probably won't become visible again, unless future observers are more sensitive. As for predictability, according to https://www.space.com/1258-predicting-bright-comet.html:

Right now, somewhere out there in the depths of space, a Great Comet is approaching the Sun. Unfortunately, we can have no advance knowledge of when it will appear until it is discovered on the inbound leg of its solar journey. Most of the dim periodic comets travel in small elliptical orbits and regularly return to the Sun's vicinity at intervals of generally a dozen years or less. But Great Comets swing out far beyond the orbit of Pluto and usually require many hundreds ... or even thousands of years between visits to the Sun.​

 

[davenn]

and I think that Mr. Dickinson didn't fake the photo that he posted, and that even though it was taken with a camera lens, the photo adequately evinces the fact of the visibility to the unaided eye.

I never suggested he did fake it, I have been doing astrophotography for 50 years. I know that photo
is easily possible to do specially with a bit of processing to bring out the details

Again, this is the bit that is not good ...
Nooo, you cannot make that assumption, the camera will pick up stuff not visible to the eye.
Again, this is very misleading.
Dave

 

[sysprog]

I made that supposition based on the comparative size of the moon in the image.

 

[davenn]

I made that supposition based on the comparative size of the moon in the image.

that's reasonable, if you don't have experience in astro photography, but what you probably don't
realise is that there was a significant telephoto lens used The size of the moon using a standard lens,
anything less than 100mm focal length ... will produce a VERY small captured image. I wouldn't be surprised
if the lens was a 150mm or more focal length. D

 

[DaveC426913]

A comet is an asteroid that got close enough to the sun to incandesce.

At the risk of being pedantic, this is not really true.
Comets and asteroids are characterized by their composition.

Comets can become quite visible as their volatiles offgas.
An asteroid, mostly heavier rock and metals, would have to get uncomfortably close to the sun before it would offgas or incandesce.[ EDIT ] Sorry. I see another Dave has beaten me to this, and it has been addressed. Carry on.