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6
votes
1answer
94 views

If water vapor is always blown away into space, how is it able to create chemical compounds on Venus?

This is the follow-up of this chem.SE question. According to Wikipedia, water vapor on Venus is present in trace amount (20 ppm). There are multiple reasons why Venus has very low water content: The ...
1
vote
1answer
22 views

What is the difference between these various Angular Resolution formulas?

I have recently learned about angular resolution and its dependence on the ratio λ/D. There seem to be three different equations for angular resolution that I have come across. One of these has the ...
1
vote
0answers
120 views

Is it possible to generate random numbers from images of the sun? [closed]

If this is off topic, please change it to world-building. Is it possible to make a low cost heliography telescope, which is not digital, and which can be used to generate an worldwide numerical ...
1
vote
1answer
63 views

Is a literal instance of Russell's teapot possible?

Much has been said about Russell's teapot, and I accept as obvious that a teapot would be too small to be detectable in an orbit around the Sun by any reasonable method today, or by any method that ...
1
vote
1answer
20 views

How accurate is Stellarium at depicting the Earth, from the Moon, approaching a solar eclipse (from Lunar perspective)?

This is how Stellarium depicts the positions of the Earth and Sun 24 hours before the solar eclipse (from Lunar perspective) on Jan. 13, 2131 A close up of the Earth on that day (Jan 12) shows no ...
0
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0answers
12 views

Should galaxy clusters of the same richness class have a similar total mass of super and ultra massive blackholes within their galaxies?

I was looking into the masses of black holes and as we know more about our local space then further away or obscured clusters there is less information available for those clusters individual galaxies....
4
votes
2answers
55 views

Small changes to Earth's orbit caused by a large impact on the Moon

Is there any scenario where a large impactor striking the far side of the Moon would perturb the Earth's orbit enough to reduce the distance from the Earth to the Sun and still remain within the ...
3
votes
1answer
31 views

Can you see both Jupiter and Saturn (and their moons) in detail during their upcoming conjunction?

In December of this year, Jupiter and Saturn are going to be in a conjunction. Are they going to be close enough that you could resolve both as more than just dots and see their respective satellites ...
1
vote
1answer
216 views

How do scientists confirm iron core at the centre of the earth? [closed]

How do scientists confirm iron core at the centre of the earth? We know scientists couldn’t yet drill to the core of our planet earth. Yet we know they confirmed there is a core of iron at the centre ...
2
votes
2answers
83 views

Does time also pass more slowly for a galaxy that is traveling at relativistic speeds, where the speed difference is due to Hubble expansion?

If time passes more slowly, relative to Earth, for a traveler at relativistic speeds, say at .8c, traveling between stars inside this galaxy, does time also pass more slowly for a distant galaxy that ...
2
votes
0answers
21 views

Can the order of planets change in a young planetary system?

The Nice model and the Grand Tack model both show that the distance between a planet and its host star can change greatly over time. Is it possible in either of these models for the order of planets ...
1
vote
0answers
30 views

How is spectroscopy used to deduce what an object is made of?

Spectroscopy is an analysis of light (or other EM wavelengths) that is often used by scientists to examine what an object is made from or contains. Apologies if this is a stupid question, but this ...
5
votes
1answer
165 views

Did I see a meteor or a re-entry?

Last night (January 21, 2015, possibly 5:30 UTC), from my house in northern California, I saw a moving point of light in the sky, going west to east, crossing about 120 degrees of sky in 5 seconds or ...
9
votes
2answers
469 views

Could an impact have resurfaced Venus 300 million years ago?

Venus surface isn't older than about 300 million years. The only explanation I've come across is that some kind of global volcanism resurfaced the planet. But couldn't it have been an impact event? A ...
0
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0answers
33 views

Binned of phase-folded light curve

How I can bin a magnitude phase-folded lightcurve? I take mean values magnitudes and it's uncertainties but this is wrong.
1
vote
1answer
31 views

Why is the SETI survey limited to only Red Dwarf Stars?

I was going through the official SETI website, when I came across this article on the same website which said : Today, the SETI Institute uses a specially designed instrument for its SETI efforts – ...
2
votes
0answers
41 views

What other hints of possible life in Venusian atmosphere have we dismissed?

Now that phosphine has probably been discovered in relatively large quantities in the Venusian atmosphere, I heard that there have been other unexplained phenomena (i.e. dark patches) seen. Does ...
1
vote
0answers
34 views

Satellites in a row [duplicate]

I often watch the night sky in central North Dakota and love seeing satellites zooming by. Recently I saw a string of satellites traveling SW to NE. There were as many as 30 traveling one after the ...
5
votes
1answer
96 views

Do the Bullet Cluster remnants prove that dark matter consists out of particles?

Some time ago the remnants of a collision between two collections of stars were discovered. These remnants are called the Bullet Cluster: The color blue (non-visible in reality) represents the ...
1
vote
0answers
31 views

Have any meteoroids been detected before they reached the Earth's atmosphere?

Once a meteoroid starts burning up in the atmosphere, it becomes a visible meteor. Have any meteoroids been detected before they started to burn in the atmosphere? If yes, what is the ballpark ...
2
votes
1answer
79 views

What was the field of view of the Ohio State University Radio Observatory of Wow! signal fame?

This answer to Did comets 266P/Christensen or P/2008 Y2 (Gibbs) cause the Wow! signal? points out that the comets in question were nowhere near where the radio telescope was pointed. Wikipedia says ...
4
votes
2answers
228 views

Can anyone one show how speeds greater than c cause a paradox on a space time diagram?

So according to Relativity, time moves at different rates for different observers, and distant observers will actually disagree on the order of events. Now from what I gather this gets sorted out for ...
16
votes
1answer
529 views

Can any information leave a black hole?

Referring to this question, is there any information that can leave black holes? Are they causing a permanent information loss in our Universe?
5
votes
0answers
85 views

Is the 1970's Viking Orbiter due to contaminate Mars? [closed]

From Wiki: The Viking program ended on May 21, 1983. To prevent an imminent impact with Mars the orbit of Viking 1 orbiter was raised on August 7, 1980 before it was shut down 10 days later. Impact ...
2
votes
0answers
76 views
+100

How are small objects automatically identified and their locations determined in digital images?

I have a large quantity of old digital images of low energy electron diffraction (LEED) patterns that I must process to identify and locate small, sometimes elongated gaussian-like blobs of a few ...
1
vote
1answer
123 views

What is this planet or satellite in this picture?

I took this photo in Shijiazhuang, Hebei Province, China, 38°13'N 115°18'E (+38.23, +115.31) on the night of February 8, 2020. Here you can see a round object above the moon, and it was moving fast,...
1
vote
1answer
48 views

How many tsunamis have been caused by meteorites falling?

I don't know if this is a better fit for Earth Science (because of the tsunami part) or for Astronomy (because of the meteorite part). The Wikipedia page on tsunamis says that tsunamis can be caused ...
4
votes
0answers
25 views

Does the Draco supercluster influence the cosmic flow paths of local structures?

I was wondering if the Draco supercluster which lies around 1.5 billion lightyears away is known to effect the paths of any of our local superclusters? Other than the Shapley, Horologium and Caelum ...
21
votes
5answers
4k views

Was the Geocentric Model correct at all?

It's easy to find resources stating that the heliocentric model is right and geocentric is wrong. But how wrong was it? Was it correct in any way? It was built on incorrect assumptions, but despite ...
27
votes
2answers
6k views

How did Eratosthenes know that the sun is far away?

The famous measurements and calculations done by Eratosthenes around 300 BC are very widely known. He concluded correctly that the circumference of the Earth is about $252\,000$ times the length of an ...
2
votes
1answer
111 views

Why dimmer high-redshift supernovae means the expansion is accelerating, if the dilated region pertains the distant past?

I must be seeing this wrong, because it seems to me the data indicates faster expansion in the past, contrary to Adam Reiss' study that led to the birth of the notion of 'dark energy'. In Reiss' ...
33
votes
3answers
7k views
+50

Why do the planets in our solar system orbit in the same plane?

(Yes I'm excluding Pluto from this the same way it was excluded for not being a planet) Observing the planets orbit of the Sun they all seem relatively planar and roughly all orbit along the same ...
2
votes
1answer
73 views

Is there a possibility of finding a system where a star is orbiting a planet?

Is it possible for a star to orbit a planet IF the planet is bigger than the said star? Or is it possible even if the star is bigger than the planet and still the star is orbiting the planet? I have ...
0
votes
0answers
46 views

Can Big Crunch happen without net loss of energy/mass? [closed]

Just like any other explosion, the matter that started moving first in the explosion will be the farthest to go. Assuming there are no multiple Big Bangs, will the first left matter ever come back to ...
1
vote
1answer
95 views

I saw a weird thing around Venus

I pointed my telescope (50mm aperture, 500mm focal length, 4mm eyepiece, image taken through a window) at Venus and saw this: What is it? I don't think this is Uranus or Neptune as my telescope is ...
3
votes
1answer
33 views

I have seen so many articles but how can finding exoplanet density determine composition

I have seen some articles and lectures that state but i cant seem to put my finger on on how does density affect composition and how are you able to determine composition from exoplanet density.
20
votes
1answer
2k views

How long between the moment a meteor is first visible and the moment a meteorite hits the ground?

A meteor is usually only visible for a couple seconds at most, but I would guess that it usually stops being visible high above the ground. Meteors often don't make it to the ground as they completely ...
0
votes
1answer
22 views

Who coined the phrase “martian dichotomy”?

This question is adjacent to this other one. The martian dichotomy refers to the fact that the northern and southern hemisphere are radically different on Mars, with different surface ages and ...
0
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0answers
24 views
+50

Relation between photometric redshift in a given bin and conditional probability

I take over an old question that is not yet clear for me. Indeed, I would like to formulate the equation (1) below under the form of "conditional probability" but I can't manage to do that. ...
-1
votes
0answers
11 views

Difference between Skywatcher EQ3 and EQ3-2 mount

Is there any difference between the Skywatcher EQ3 and EQ3-2 mount? I have this EQ3-2 mount and I am considering buying the GoTo Upgrade kit. However, the GoTo upgrade kit for the EQ3-2 is sold out in ...
13
votes
3answers
3k views

How is it possible that Saturn's gravitational acceleration felt by Mimas is stronger than Mimas' own surface gravity?

The surface gravity on Mimas is $≈ 0.063\text{ m}/\text{s}^2$ and Saturn's gravitational acceleration at the distance of Mimas' orbit is: $$\frac{{GM}}{{r}^2} = \frac{{6.674 \times 10^{-11} \times 568....
0
votes
0answers
12 views

Accretion and Flyby Simulation Software

I want to simulate a close encounter between a star and a black hole, using Smoothed Particle Hydrodynamics (SPH). How can I simulate the flyby of a star/compact body around a Black Hole? How to ...
7
votes
0answers
77 views

What are the prospects for follow-up observations of phosphine on Venus?

Today, it was officially announced that astronomers have detected phosphine on Venus via the $\text{PH}_3(0\to1)$ transition (Greaves et al 2020). While the line was found by both the James Clerk ...
3
votes
0answers
36 views

Is dust the only reason why the Martian sky is so bright?

The atmospheric pressure on the surface of Mars is 0.00609 atm on average and 0.012 atm at most in the Hellas Basin. On Earth, at these pressures, which are found at altitudes about 30-35 km (19-22 mi)...
2
votes
0answers
21 views
+50

Observed instances of massive gas inflow and AGN restart due to cluster-cluster merger?

Works such as Acreman et al. (2003) have demonstrated via simulations the possibility of gas being stripped off a galaxy due to interaction with a galaxy cluster. Have there been confirmed instances ...
12
votes
3answers
1k views

Can two heavy objects circling around their C.M. be separated because of the speed of gravity?

Imagine two massive objects, with the same mass (M) circling around their center of mass (C.M.). Let's assume that the distance between them is 1 light hour. Don´t the two bodies get accelerated and ...
7
votes
2answers
125 views

Phosphine on Venus?

For the purposes of this question, let's assume that the team really have detected phosphine. My question is how do we know that phosphine is on Venus, and not closer to home? I've just found out a ...
10
votes
6answers
5k views

Did I see a supernova explosion?

I think I just saw a supernova explode with my own eyes through my GSO 12 inch Dobsonian. Please tell me what it was! I am still trying to find what it was it was mindblowing! I went out on my roof ...
5
votes
2answers
61 views

Could a Trappist-like planetary system exist around a sun like ours?

So, a couple of years ago, the TRAPPIST sun was discovered to have 7 different earth-like planets orbiting it – three of them in the habitable zone. Nothing like this has ever been seen before, or ...
0
votes
1answer
31 views

Relation between age and spectral type of star

Does the spectral type of a star change as it ages? Since its temperature changes, I suppose the spectral type should also change, but I'm a bit confused about this. Also, is the spectral type ...

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