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103 votes
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Did I see Pluto with my naked eye?

Pluto is something like magnitude 14. The limit for the human vision is somewhere between magnitude 6 (widely accepted) and 8-ish (highly trained observers with perfect vision in ideal conditions ...
Florin Andrei's user avatar
101 votes
Accepted

Could the dinosaurs have seen the asteroid that killed them?

The answer is yes; for a few nights prior to the impact (assuming they had eyes with a similar sensitivity to our own and could look up!). It could be a bit longer than this if the body was larger ...
ProfRob's user avatar
  • 155k
40 votes
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Is the Sun visible from Proxima Centauri to human eyes?

Well, there's two things we'll need for this: apparent magnitude (the brightness that an object appears to have) and absolute magnitude (the actual brightness an object has). Both of these scales are ...
Sir Cumference's user avatar
35 votes
Accepted

Will just a glimpse (less than a second) of sun during partial solar eclipse damage eyes?

Glancing at a partial solar eclipse is about as dangerous as glancing at the Sun on any other day. If you look at the Sun a few minutes after sunrise or a few minutes before sunset, when the Sun's ...
PM 2Ring's user avatar
  • 15k
31 votes
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Can Pluto be seen with the naked eye from Neptune when Pluto and Neptune are closest?

No, it cannot. Far from it. The closest approach between both planets is roughly 16 AU due to the 3:2 orbit resonance. Pluto will even then be a tiny dot among many with a brightness around 14 mag. ...
planetmaker's user avatar
  • 19.9k
29 votes

Why is it okay to watch a sunset but not an eclipse?

During a sunset, the Sun is lower in the sky than during most of the day - much lower. Therefore, light from the Sun travels through about 120 miles of dense atmosphere, compared to the roughly 2 ...
HDE 226868's user avatar
  • 37.2k
18 votes

Did I see Pluto with my naked eye?

As Florin correctly stated, it can't have been Pluto. You have probably looked at it and you have even gotten its light in your eyes. That little itty bitty shine just has no chance to make your ...
Haunt_House's user avatar
16 votes

Can Pluto be seen with the naked eye from Neptune when Pluto and Neptune are closest?

According to the NASA Pluto fact sheet, the brightest that Pluto gets is an apparent visual magnitude of 13.65 when it is 28.6 au from the Earth and (presumably) about 29.6 au from the Sun. To work ...
ProfRob's user avatar
  • 155k
14 votes

Have there been successful attempts at spotting Neptune with the naked eye?

Well, having seen Neptune and identifying Neptune are two totally different things. Let's tackle this one step at a time. Your link says: From these observations it would appear that, if seen upon ...
Sir Cumference's user avatar
14 votes

Will just a glimpse (less than a second) of sun during partial solar eclipse damage eyes?

This webpage gives a lot of background information. Key points: It does seem to be the overall dimness of near-total eclipses that allows the pupil to widen enough to allow damaging levels of UV in. ...
Mark Foskey's user avatar
  • 3,916
13 votes

Could the dinosaurs have seen the asteroid that killed them?

A carbonaceous condrite has the same reflectivity as the moon at around 7-13%. If there was ice, if the tail was 10 times smaller than Hale-Bopp, it would have auspiciously covered half of the sky. ...
bandybabboon's user avatar
  • 4,268
12 votes
Accepted

Will Asteroid (2021 LD6) be visible to the naked eye?

No, at its brightest in June 2021, 2021 LD6 [MPC, JPL] was apparent magnitude 20-21, well beyond the reach of most amateur telescopes. At absolute magnitude H=27.3, it's not very large, and at 10.5 ...
Mike G's user avatar
  • 18.7k
8 votes

Why is it okay to watch a sunset but not an eclipse?

There is also a second reason for this. The density of the atmosphere decreases as you go up in the atmosphere. At sunset, the sun's rays hit the atmosphere at an angle and refract through the ...
mmainville's user avatar
8 votes

Are meteors visible on Mars?

First Shooting Star Seen from Mars space.com 2005 The background image shows the meteor near the top-left and the horizon at the bottom. A red arrow shows the direction of travel. The inset ...
Keith McClary's user avatar
8 votes
Accepted

What objects in the night sky have the narrowest range of visible light

...the narrowest spectrum of visible light... is tough because most process that make electromagnetic radiation either result in broad continua or multiple emission lines. I originally wanted to ...
uhoh's user avatar
  • 30.7k
7 votes
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Mars night sky -- Phobos and Deimos?

Taking Mars' average distance from the sun of 1.52 AU, the sun would be 43% as bright. Phobos has an albedo of about 0.071 which is pretty dark. Darker than the Moon with an average albedo of ...
userLTK's user avatar
  • 24.1k
7 votes
Accepted

How easy would be to see the Moon from Mars?

We have pictures of this, thanks to Curiousity! (Source) “A human observer with normal vision, if standing on Mars, could easily see Earth and the moon as two distinct, bright “evening stars,” ...
Cody's user avatar
  • 1,180
7 votes

Will the nebula of Betelgeuse be visible to the naked eye? How bright, how large, how soon, for how long?

There is an article here that describes the visible effects quite well. In essence, within a week or so, it would be comparable in brightness to the moon and therefore visible during the day. ...
sforsingh's user avatar
  • 1,443
7 votes

A what distance could we see the Sun?

I agree with your naked eye figures, but the sensitivity of JWST has been over-estimated - it could "see" the Sun at 4 million light years. The Sun has an absolute visual magnitude of about ...
ProfRob's user avatar
  • 155k
6 votes

Is the Sun visible from Proxima Centauri to human eyes?

Alpha Centauri A and B happen to be rather similar to Sol, and their absolute magnitudes are 4.38 and 5.71 respectively (Wikipedia). Add them together and you get absolute magnitude 4.10 (the scale ...
Anton Sherwood's user avatar
6 votes
Accepted

Could Ganymede's aurora be seen with the naked eye?

The aurora depicted in the artist's conception is of ultraviolet light. It would not be seen with the naked eye. "NASA's Hubble Space Telescope observed a pair of auroral belts encircling the Jovian ...
Bob516's user avatar
  • 1,489
6 votes
Accepted

Can Mercury be seen from the 60th parallel north on Earth? Shetland, Faroe, Norway, St Petersburg, Alaska

Yes it can be seen, but as the angle of the ecliptic is lower in more Northern Latitudes it is harder to see. Chris Brown of the Shetland times writes in Feb 2000: February brings a chance to try and ...
James K's user avatar
  • 125k
6 votes
Accepted

Can Jupiter's rings be seen with the naked eye by an astronaut nearby? How difficult would it be?

Here is an answer based on photometric arguments: The astronaut probably would not be able to see the rings, but it would be worth a try. I would recommend the astronaut float somewhere at a distance ...
giardia's user avatar
  • 2,098
6 votes
Accepted

How many planets can be seen by the naked eye?

The faintest we can see is magnitude +6.5 Here are the apparent magnitudes of planets at their brightest, I've boldened the ones that fall within visible range: −4.92 planet Venus −2.94 planet Jupiter ...
Rabbi Kaii's user avatar
6 votes
Accepted

Is Uranus the farthest object in Solar System that you can see with naked eyes?

Yes, apart from maybe Neptune, which is within the "extreme naked eye limit", there are no other objects further than Uranus that have an apparent magnitude above +8. See this list: https://...
Rabbi Kaii's user avatar
5 votes

Will we be able to see our galaxy if we travel far enough?

In theory, yes; in practice probably not ... i) It's perhaps helpful to take the Andromeda galaxy as a first working example. It is somewhat bigger than our own Milky Way galaxy but not so big as to ...
MartinV's user avatar
  • 644
5 votes

Is the Sun visible from Proxima Centauri to human eyes?

The key to this is the so called Absolute Magnitude, which represents the visual magnitude from a distance of 10 parsecs (about 32 light years). The sun is much brighter than Proxima Centauri. It has ...
Dr Chuck's user avatar
  • 4,349
5 votes
Accepted

Is it safe to view a solar eclipse with eyeglasses along with eclipse glasses?

Yes, it's safe :). Your eyeglasses are just correcting your vision. The net effect is just to give the equivalent of normal vision - and in any case, you'd normally be holding the eclipse glasses in ...
JerryTheC's user avatar
  • 654
5 votes

Can Pluto be seen with the naked eye from Neptune when Pluto and Neptune are closest?

That's great question! ... I'm just thinking that just for comparison, Pluto is roughly 70% the diameter of our Moon and Pluto would be far away from Neptune than the Moon is from Earth. Moon is also ...
Daniel Morales's user avatar

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