2
votes
3answers
116 views

Which is really larger, Big Dipper or Small Dipper, in 3D

If we take the convex hull of the 3D coordinates of the stars in Ursa Major and Ursa Minor: which hull has larger volume? This is meant semi-humorous but we might also learn some interesting points ...
4
votes
1answer
160 views

What is the bluest narrow band filter mounted on ground based telescopes?

If we want to check a QSO's lyman alpha narrow band image, could a ground based telescope do that? I mean under the circumstance that its lyman alpha shifts to 3300A.
3
votes
1answer
26 views

What happens to the Gas Pressure when working out the Eddington Luminosity?

I am looking at how the Eddington Luminosity is derived and I do no understand why we only care about $P_{rad}$? When working out $L_{Edd}$ you take the ratio between $dP_{rad}/dr$ and ...
2
votes
4answers
511 views

Which is more rare: Lunar eclipse or Solar eclipse?

Which is more rare: Lunar eclipse or Solar eclipse? Please explain why either one is more rare than the other. Thank you in advance for your inputs.
2
votes
1answer
95 views

Stars in the sky

Are the stars we can see with the naked eye in the night sky only from our Milky Way galaxy or can we see stars from Andromeda? I am aware we can see other celestial objects like nebulas and the ...
-1
votes
1answer
26 views

Two body transient solution

In the two body problem, if each body is given an initial condition as a momentum vector, what is the transient part of the solution as it settles into the steady state orbit?
5
votes
1answer
586 views

How was the Earth-Sun distance originally calculated?

AFAIK it was possible long before the first interplanetary probes. Who did it?
4
votes
1answer
172 views

Why can we see stars but not astronaut on the moon

A question came up today in astronomy class and it got me wondering all night. How is it that if stars are so far away, we can see them so clearly but we cannot see astronauts on the moon.
10
votes
3answers
180 views

Blowing up an asteroid/comet really potentially worse?

Often on television shows and in articles I see it mentioned that it'd always be bad to blow up an asteroid or comet because then the energy would just be spread out and cause even more damage. ...
2
votes
1answer
241 views

is there any theory or observational evidence that our universe is electrically neutral or not?

It seems our universe is neutral in large scale. There is CP violationwiki problem about matter and dark matter. Similarly is there any theory about whether our universe is electrically neutral? ...
1
vote
2answers
219 views

Life planets orbiting black-holes. Can/Do they really exist?

So, I watched Interstellar and if you watched it too you know that there's a planet orbiting a black-hole, they call it Miller's Planet. According to the movie, every hour on Miller's Planet is ...
2
votes
1answer
97 views

The tidal locking problem concerning Earth sized planets in habitable zone around Red Dwarfs

Would twin planets orbiting around each other present a solution to tidal locking of habitable planets in red dwarf systems? It's an awfully easy equation to set up. I'm fibbing; I can't do it. I was ...
0
votes
1answer
53 views

why does venus flick?

I was watching Venus with the naked eye yesterday at about 7 pm and I noticed that it was flickering, almost like a star. I have always learned that planets don't flicker to the naked eye, only stars ...
1
vote
1answer
41 views

When is Gamma Draconis closest to the zenith in London on April 4th

I am reading Roobert Hooke's paper An attempt to prove the motion of the earth from observations (1674, faksimile). Hooke writes The principal dayes of doing which will be about the 4 of April, ...
1
vote
4answers
131 views

Is there a way to tell what the surface of a planet is like?

Kepler-442b I'm doing a project in which I need to find a planet within our galaxy that might be habitable. I found this planet that is within its stellar system's habitable zone, and due to research ...
1
vote
2answers
60 views

Calculating the age of the universe

Is the calculated age of the universe that of the visible universe or the entire universe? I dont know how the age is calculated but if it is believed that all we see visibly IS the entire universe ...
5
votes
2answers
464 views

How can the sun burn without oxygen?

Allright I am a 17 year old student, that only just figured out that the universe is amazing! Thanks to Dr. Neil Degrasse Tyson I raised a lot of interest in the universe. Due to his latest show ...
3
votes
2answers
1k views

What would happen if Jupiter and Earth were at the same distance as the Moon is from Earth?

If Spock came with a super machine capable of moving planets, and placed Earth so close to Jupiter as the Earth's moon, the gravity of Jupiter would make us fall into it?
3
votes
1answer
79 views

Evolution of the Hubble parameter

In the lambda-CDM model describing an accelerating Universe, the Hubble parameter is currently decreasing with time. Will it continue to decrease forever?
19
votes
3answers
4k views

Why there is no smoke around the Sun?

Where there is fire, there is always smoke. So why there isn't any smoke near the Sun?
2
votes
2answers
95 views

Claim that 30-m class telescopes will have resolution far superior to Hubble: true?

This article makes the claim that the Giant Magellan Telescope (GMT, number 4 in the list) will have resolution 10 times better than that of Hubble, while the Thirty Meter Telescope (TMT, number 3 in ...
4
votes
5answers
858 views

What would the effects be on Earth if Jupiter was turned into a star?

In Clarke's book 2010, the monolith and its brethren turned Jupiter into the small star nicknamed Lucifer. Ignoring the reality that we won't have any magical ...
0
votes
1answer
47 views

Cosmological deflation?

Wikipedia tells us: In physical cosmology, cosmic inflation, cosmological inflation, or just inflation is the exponential expansion of space in the early universe. The inflationary epoch lasted ...
-1
votes
0answers
26 views

What are the implications from the fact that Relativity and QM did not predict intergalactic space, big bang, inflation or dark matter? [closed]

Cosmology has two very successful theories, Quantum Mechanics and Einstein's theory of Relativity. But they are unrelated to each other. And their predictive powers have been limited, being equally ...
0
votes
1answer
31 views

Can you assume atmosphere height for the purpose of surface pressure calculation?

Given that by definition of scale height an atmosphere thins by a factor of 1/e^x where x is elevation in terms of scale height multiples (See the table here: Definition of Scale Height), can we ...
0
votes
1answer
13 views

Is it possible to get the distance to a star in the IPHAS DR2 catalog?

I'm looking at the IPHAS DR2 catalog. It has the Right Ascension and Declination but I'm not seeing any distance information (lightyears or parsecs). I'm wondering, given the columns in the dataset, ...
11
votes
1answer
242 views

Where is Voyager 1 (or 2) going? In which direction?

Knowing it has exited the solar system, is it traveling in the direction of the center of the galaxy, away from it, orbiting it, or maybe even going perpendicular from the disk-shaped galaxy?
4
votes
1answer
80 views

Missing Terms in Weinberg's treatment of perturbations on Newtonian Cosmology

I was reading Appendix F of Steven Weingberg's book "Cosmology". In this Appendix he works out the perturbations to a cosmological fluid described by non-relativistic hydrodynamics and Newtonian ...
4
votes
2answers
372 views

How to plot orbit of binary star and calculate its orbital elements?

I have a set of dates, position angles ($\theta$) and angular separations ($\rho$) for visual binary star. For example: ...
10
votes
2answers
126 views

How far apart is the dust in the Sombrero Galaxy's dust lane?

In his answer to this question, TildalWave made this remark: I think that first, we have to properly appreciate the size of the Sombrero Galaxy. It is roughly 50,000 light years (15 kilo parsecs) ...
0
votes
0answers
46 views

What would this moving point of light be?

Tonight (10:00 PM EST Middlesex County, Mass.) when looking at the mostly clear sky I observed what I at first believed was a meteor. This point of light was moving east to northeast and that would be ...
0
votes
0answers
33 views

How to implement DCDFT to get S vs T graph

I was trying to implement DCDFT (Date Compensated DFT) (Ferraz Mello's) to a tabular data which I had saved in an Excel file. After searching the internet thoroughly, I came across Vstar software, ...
6
votes
0answers
32 views

Why doesn't the New Horizons probe fly any nearer than 10,000 km from Pluto? [migrated]

New Horizons is intended to pass within 10,000 km of Pluto on its flyby on July 14. This will give a maximum resolution on the surface of 50m per pixel. This seems to me a bit of a waste, when it ...
1
vote
0answers
34 views

Use Pluto's gravitation to reach the next dwarf planet [migrated]

Why doesn't New Horizons fly by nearer to Pluto so the gravitational pull would slingshot the probe to one of the next dwarf planets in the outer solar system (Eris, Haumea, Makemake,...)? I would ...
1
vote
1answer
96 views

what is a Friedmann model?

Can you explain what is a Friedmann model to a layman? And also give some examples of Friedmann models, specially I would like to know if the lambda-CDM model is considered a Friedmann model.
13
votes
1answer
1k views

Why do some planets have rings?

Some planets, specifically Jupiter, Saturn, Uranus, and Neptune in our solar system, have planetary rings. Why do some planets have rings? How are they made and from what? Most importantly, will I ...
0
votes
0answers
21 views

Tonight sky - deep sky objects

programmatically how can i get the list of Deep sky objects that will transit the meridian in my Latitude and longitude? Any online API?
7
votes
6answers
125 views

Determine the moons of Jupiter through a telescope

I was doing my own "space exploration" last night with a telescope. Being a space noob I can't visually determine stars or planets (I know the moon, though), but I focused on one particularly bright ...
1
vote
1answer
84 views

What uncertainty does an error bar signify in astronomy?

When an astronomer talks about her/his topic and shows an X/Y-plot with error bars. What should one assume that those error bars represent? 1 standard deviation? Or 2? Or some specific significance ...
3
votes
1answer
112 views

How much mass will the white dwarf sun have compared to our current sun?

In 4 billion years, when our sun sheds all of it's outer gas layers and turns into a white dwarf, how much mass will the white dwarf have compared to what the sun has today? Will the planets still ...
1
vote
1answer
75 views

How can I calculate how the debris of an object ripped apart at the Roche limit will spread out?

Let's say I have a moon orbiting a planet at a distance $d$. Eventually, $d \leq d_R$, where $d_R$ is the Roche limit of the moon-planet system. I can figure out the mass of both bodies by experiment, ...
1
vote
2answers
107 views

On a log-log plot of surface gravity to planet mass, what is the meaning of the y-intercept?

I am playing around with data from exoplanets.org, and am interested in the plot of surface gravity to planet mass. I reproduced this plot after downloading their data and performed a non-linear ...
8
votes
1answer
96 views

What percent of planets are in the position that they could be viewed edge-on from Earth? (and thus able to undergo transits)

Star number 12644769 from the Kepler Input Catalog was identified as an eclipsing binary with a 41-day period, from the detection of its mutual eclipses (9). Eclipses occur because the orbital ...
7
votes
6answers
5k views

Did atoms in human body indeed come from stars?

I think I am not alone who saw videos about that we (humans) are made of same atoms which someday were in stars. In other words, some atoms in our bodies are from stars which exploded billions of ...
8
votes
4answers
263 views

How would we detect an Earth doppelganger planet?

With our current technology, or technology available in the near future (up to 2025), how would we detect a planet exactly like our own, and how close would it have to be to be detectable? Which ...
0
votes
1answer
45 views

Can close binaries have a very eccentric orbit?

For example, are there binaries with an orbital period < 5 day and that are very eccentric? What kind of factors could slow down orbital circularisation? Are ...
1
vote
4answers
87 views

Image sets for testing stacking algorithms?

I am looking for sets of astronomical images for testing different kinds of stacking algorithms. The idea is simple: if one has $N$ images of the same object, the signal-to-noise ratio of the ...
0
votes
1answer
41 views

What is the most populated/numerous stellar system in which the orbits of all objects are known?

I posed a question or two on here a couple months or so ago about the orbital patterns of each of the seven stars in the two septenary star systems Nu Scorpii and AR Cassiopeiae. They remain ...
1
vote
0answers
46 views

Telescope Problems

I currently own a telescope, I'm an amateur astronomer and currently just trying to view the moon. I own the Celestron PowerSeeker 70AZ. Link for information on the telescope: ...
6
votes
2answers
139 views

Why does the Solar System have no (natural) satellites of satellites?

What are the conditions for a planetary moon to have a satellite of its own? How far do the Solar System's bodies fall from the necessary threshold?

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