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37 votes

Is Venus' north towards Earth's south

This is a matter of defintion and convention, not science. By convention "North pole" is defined to be the pole that lies to north side of the solar system's "invariable plane" (...
James K's user avatar
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35 votes
Accepted

Can the Moon eclipse Venus?

As @Donald.McLean said in comments, the answer is yes, the Moon can and does occult the other planets in the Solar System. When something apparently big (like the Moon) passes in front of something ...
Mick's user avatar
  • 1,410
34 votes
Accepted

How was the mass of Venus determined?

How was the mass of Venus measured for the first time? In the mid 19th century, Urbain Le Verrier's predicted of the existence of a then unknown planet beyond the orbit of Uranus. He even predicted ...
David Hammen's user avatar
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32 votes
Accepted

Why is Venus's atmospheric pressure 75 times that of earth when carbon dioxide is only 1.5 times heavier than air?

Venus's atmosphere is very dense at the surface because Venus's atmosphere is very massive. The composition is nearly irrelevant. The pressure at Venus's surface is proportional to the mass of Venus's ...
David Hammen's user avatar
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32 votes
Accepted

Why is it impossible to infer the surface temperature of Venus by spectroscopy observation from earth?

The important difference is that the word "surface" has a different meaning depending on whether we're talking about the Sun or Venus. When we say "the surface of the Sun," we ...
Tanner Swett's user avatar
29 votes

Is Venus in some way tidally locked to... Earth?

@BMF's comment links to (Gold & Soter 1969) Icarus 11, (3), November 1969, pp 356-366 Atmospheric tides and the resonant rotation of Venus. Since it is paywalled I'll add a short summary: From ...
uhoh's user avatar
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25 votes

Why doesn't the IAU definition of "Planet" disqualify Mercury and Venus as planets?

You are citing a paper that has been cited only six times in the peer reviewed scientific literature since it was published in 1984, which was almost 40 years ago. One of those six citations was a ...
David Hammen's user avatar
  • 33.7k
21 votes

How was the mass of Venus determined?

The mass of Venus was determined by weighing the Earth, or more precisely, by determining the ratio of the density of the Earth to the density of Schiehallion, and assuming Schiehallion to be typical ...
Mark's user avatar
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19 votes
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How could Mars' atmosphere be shed by solar winds, when Venus has a thick atmosphere despite no magnetic field?

I am not certain that the main cause of Mars losing most of its atmosphere was the solar winds. Long before the solar wind was discovered scientists calculated other factors which affect how long a ...
M. A. Golding's user avatar
18 votes

What would happen if Venus and Earth collided?

This is the kind of thing that computer simulations are done for, but I am not aware of any that were specifically for a Venus-sized body hitting the earth. The specific details would depend very much ...
Mark Foskey's user avatar
  • 3,896
18 votes

What would happen if Venus and Earth collided?

The outcome of a Venus - Earth collision depends on the impact speed. At a relatively low speed, the matter is likely to condense to form a new planet. But if the speed is high enough the planets will ...
PM 2Ring's user avatar
  • 13.6k
18 votes

Why is it impossible to infer the surface temperature of Venus by spectroscopy observation from earth?

I think the problem is that spectroscopy at visible and infrared wavelengths simply can't penetrate the thick atmosphere of Venus. Thus the information comes from much higher in the atmosphere and not ...
ProfRob's user avatar
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16 votes

Is Venus in some way tidally locked to... Earth?

This is a fun little problem that's remarkably close and the math is pretty easy when you use the right periods. Venus' synodic period, relative to Earth, is 583.92 days on average. He uses 584, but ...
userLTK's user avatar
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14 votes

How could Mars' atmosphere be shed by solar winds, when Venus has a thick atmosphere despite no magnetic field?

One of the main loss mechanisms of atmospheres escape is thermal escape (Jeans escape) into space. The average thermal velocity at a given temperature $T$ for a molecule of mass $m$ is $$ v_{th} = \...
planetmaker's user avatar
  • 18.9k
14 votes

Why doesn't the IAU definition of "Planet" disqualify Mercury and Venus as planets?

I directed this question to Mike Brown, and he answered on Twitter. Mike Brown is about as authoritative as possible. The real answer here is to not get too hung up on definitions, which I admit is ...
Schroeder's user avatar
  • 513
14 votes

What is the ring of light around the moon and which star seen near it?

If the photo is from today (24 November 2023), then the "star" is Jupiter, a planet. It's hard to see any ring around the moon in the photo, but rings are typically due to high clouds, and ...
Dr Chuck's user avatar
  • 4,294
13 votes

Can the Moon eclipse Venus?

Yes, such events are called occultations. The Moon can occult anything within about 5 degrees of the ecliptic. The visibility of any lunar occultation is limited to a path as wide as the Moon is. ...
Mike G's user avatar
  • 18.6k
12 votes

Is Venus in some way tidally locked to... Earth?

According to Wikipedia, the orbital relationship between Venus and the Earth is coincidental and not because they are locked in a true orbital resonance, but it may be due to a true resonance in the ...
PM 2Ring's user avatar
  • 13.6k
11 votes

Are there ever any simultaneous transits of both Mercury and Venus as seen from the Earth?

As others have calculated, there are no predicted double transits. Since Venus transits for about 12 hours each hundred years (roughly), Venus is in transit for about 1/100000 of the time. Thus ...
James K's user avatar
  • 118k
11 votes
Accepted

Why do the upper-atmosphere clouds of Venus appear to have that V shape?

This is supplementary to antispinward's excellent answer and provides additional sources and a visualization from the JAXA spacecraft Atasuki. It has been shamelessly borrowed from Would it be ...
uhoh's user avatar
  • 31.2k
11 votes

Why doesn't the IAU definition of "Planet" disqualify Mercury and Venus as planets?

One subtle aspect of all this is that a "planet" need not be currently in hydrostatic equilibrium". From https://solarsystem.nasa.gov/planets/in-depth/: The IAU therefore resolves that ...
Oscar Lanzi's user avatar
  • 1,113
10 votes

Is the Earth going to evolve towards Mars' fate or Venus' fate?

Either or neither. It's impossible to tell from the present. If runaway climate change occurs, then yes, the conditions on Venus could be a potential analogue for the kind of environment on Earth due ...
christopherlovell's user avatar
10 votes
Accepted

Is the Earth going to evolve towards Mars' fate or Venus' fate?

If you are asking about short-term effects related to human's effect on the climate, the answer is (obviously) unclear. But in the very long term, Earth is likely to evolve to a more Venus-like state. ...
abeboparebop's user avatar
10 votes

How can we see Venus at night?

Before we begin: how far a planet is seen from the Sun is called elongation, and it's measured in degrees. 0° elongation means it's right on top of the Sun (or behind); 180° elongation means it's ...
Florin Andrei's user avatar
10 votes
Accepted

Is extra-planetary phosphine actually a new discovery?

You're correct; extraterrestrial phosphine is not actually a new discovery. As you said, we've known for decades (see e.g. Ridgway et al. 1976) that phosphine can and does exist in some gas giant ...
HDE 226868's user avatar
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10 votes
Accepted

Has Hubble photographed Venus in near IR? If so how does it compare to the new and exciting Parker Solar Probe image?

This web page -- "Here is why the Hubble Space Telescope only looked a few times at Venus (and why it looked at the Moon instead)" -- seems like a pretty good answer to your main question (...
Peter Erwin's user avatar
  • 16.7k
10 votes

What is the ring of light around the moon and which star seen near it?

tl;dr astrophotographers shouldn't carry their cameras in their pockets :-) I took photos of the Moon and Jupiter with my cell phone last night as well. I keep my phone in my pocket and the lens ...
uhoh's user avatar
  • 31.2k
9 votes
Accepted

Can we find rocks from Venus or Mercury on Earth?

You can think of it in terms of Hohmann transfer orbits, which define the minimum $\Delta v$ that needs to be applied to bring something from one orbital radius to another orbital radius when orbiting ...
ProfRob's user avatar
  • 149k

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