1
vote
1answer
45 views

Which is the most early type star with a planet discovered by radial velocity method?

We have discovered planets in Beta_Pictoris(A6V)here and Fomalhaut alpha(A3v)here. However they were discovered by direct images. There should be an stellar type limit by RV? What is the most ...
0
votes
2answers
95 views

Determine north just by one shadow

I am not sure if this is the right place to post at, but I tried to find the best place to do so. To my point, I wonder if it is posssible, to determine where north is, just by one shadow, that means ...
6
votes
2answers
159 views

Does matter accumulate just outside the event horizon of a black hole?

My understanding is that time slows and approaches stopping when approaching the event horizon of a black hole. I have seen this explained several places, including a brief explanation in the last ...
0
votes
1answer
73 views

A black “superhole” possibility?

When matter crosses the event horizon, it is easy to imagine that matter is torn apart into their individual components by tidal wave effects. Atoms would be ripped apart eventually. At one time, the ...
0
votes
2answers
80 views

Does Earth revolves around Milky Way?

As we know Earth rotates around Sun and Sun around Milky Way but then Sun must have some velocity/angular momentum (I don't know that much physics terms). So as Earth revolves around Sun, it must ...
2
votes
1answer
64 views

How many black holes exist?

How many black holes exist and what is their distrubtion over mass? There is a list of black holes, but I'm interested in an estimate of all black holes in the visible universe.
4
votes
1answer
144 views

When will all eight planets in our solar system align?

Ignoring expansion of the universe, entropy, decaying orbits, and interference from any bodies colliding with or otherwise interfering with their orbits, will the eight planets known planets in our ...
6
votes
3answers
62 views

Flatness of the universe?

How does inflation explain why the curvature in the early universe was flattened out and now results in a flat universe?
4
votes
1answer
105 views

How many earths fit in the observable universe?

I was pondering our insignificance, when I wondered - how how much smaller is our planet then the (observable) universe? And being as I dont know how to do the math, I'm asking it here. So how many ...
3
votes
2answers
46 views

Where can I find a set of data of the initial conditions of our solar system?

As title suggests I'm in need of a set of data of our solar system. Similar to this http://bima.astro.umd.edu/nemo/archive/#iau25, specifically dubinsky milky way-andromeda data. I'm creating a ...
-1
votes
2answers
59 views

What would happen if a planet is removed from the solar system? [closed]

More exactly what would to happen to us/Earth in general if any of the gas giants is removed by magic from the solar system ? How long would it take after such change before we notice it ? How major ...
5
votes
2answers
82 views

Why is twilight longer in summer than winter and shortest at the equinox

I recently decided to set my alarm clock to wake me up when it is "dark" out. In the end, I decided to set my clock to the earliest time that nautical sunrise is in my state (Illinois) and stick with ...
0
votes
1answer
84 views

Calculate Day of the Year for a given date

I am trying to make sense of the following formula that claims to calculate the day of the year given today's date represented by (day/month/year): ...
1
vote
2answers
81 views

Do heavier elements breakdown during supernova?

Heavier elements like gold, uranium etc. are formed at the end of a star's life. As the star explodes into a supernova, it gives rise to nebula which is the birthplace of new stars. But as the star ...
3
votes
1answer
79 views

Sun from SuperNova

I have read that our sun was created from older star(s) which had exploded in a supernova. If all the matter is travelling away from the central point of explosion, how does it coalesce back into a ...
29
votes
4answers
5k views

Is the moon only 60 pixels?

In doing research on vision, I have learned that "20/20" vision corresponds to a visual acuity of being able to resolve details 1 arcminute in size, that most people have around 20/15 vision, and that ...
0
votes
0answers
31 views

Triangular Asterism Trigonometry

Using the SIMBAD database for Alnitak, Saiph, and Sirius -- i.e.: Alnitak: FK5 coord. (J2000): RA = 05 40 45.527 DEC = -01 56 33.26; Saiph; FK5 coord. (J2000): RA = 05 47 45.389 DEC = -09 40 10.58; ...
3
votes
1answer
80 views

Motion of the sun as observed from mercury

I recently found this animation which shows the motion of sun as observed from mercury. It seems as if the sun stops in between, retraces a bit and then continues towards the west. What is the reason ...
1
vote
0answers
50 views

Faster Earth spinning speed to overcome gravity, possible? [closed]

As far as I know we stick to the surface of the Earth as its gravity is pulling us and Earth rotation is in a way reducing the gravity. At what speed should Earth be spinning so that we all get ...
1
vote
1answer
75 views

Why planet's orbit is not perpendicular or random ?

Why planet's orbit is not perpendicular or random ? It always seems each planet is revolving on the same geometric-plane around the star.
1
vote
1answer
46 views

How often do stars form?

There are many more stars in the universe than the years that the universe has been in existence, so wouldn't this mean that stars were/are forming at an astounding rate?
0
votes
1answer
74 views

Can Mercury hit Earth or Mars in the next 5 billion years?

Mercury is the most unstable planet of the solar system, with an oscillating orbital eccentricity (between 0 to 0.45). It seems there is a 1% probability in the next 5 billion years Jupiter and ...
0
votes
2answers
47 views

Is dust extinction/reddening caused by Rayleigh scattering or some other physics phenomenon (or both)?

I know from Rayleigh scattering that in the atmosphere redder photons are scattered less than bluer photons by the particles that both make up and are floating around in the atmosphere. This is why ...
4
votes
1answer
58 views

Red cresent moon

Yesterday night i witness something very strange when i looked outside the window. I saw the moon (crescent) but it was dull red and right on the horizon ,which is strange considering that it is ...
0
votes
1answer
75 views

How do we find the exact temperature of a star/galaxy?

This is a very basic question, but I am a little confused. As far as I know, the temperature of a star is analyzed based on the color of the light it emits. So, if a star is moving away from us, then ...
4
votes
1answer
58 views

Can we find out whether early Venus was Earth-like or not?

It has been speculated that Venus billions of years ago could've had a much different atmosphere with liquid water on its surface and possibly life. Partly thanks to the cooler young Sun. But is it ...
8
votes
1answer
69 views

How do scientists know that a rock found on Earth came from Mars?

There are many documented cases of meteorites being reported as from Mars. http://en.wikipedia.org/wiki/Allan_Hills_84001 While I can understand that it's possible to know if a rock originated as a ...
1
vote
0answers
30 views

Intrasolar planetary surface temperature change divergence from Earth

Considering the vast amount of insulating gas emitted by human activity on Earth without a coincident release on all other planets in the solar system as well as the phenomenon that planets in a solar ...
7
votes
3answers
159 views

Can impact craters on the moon act like giant radio telescopes?

Could large craters on the moon be used as reflective lenses for radio signals? Acting like a large radio telescope reflecting radio waves to a satellite positioned over the crater.
1
vote
1answer
55 views

Why do we not find larger quantities of helium in the Sun's atmosphere?

The Sun currently shines because H is being burned to He, and it has been doing this for about 4.57 Ga. But when we analyze the Sun's atmosphere, we do not find unusually large amounts of He. Why not? ...
16
votes
3answers
4k views

What would happen if an ice cube is left in space?

Recently I boarded a flight and noticed Outside air temperature as -53°C at an altitude of 36860ft(11.23km). I don't know what causes such a freezing temperature in that altitude but was wondering ...
4
votes
1answer
86 views

Cooling of stars

If all stars suddenly stopped producing heat (or heating up) which stars would cool to absolute zero first and how long would it take?
1
vote
0answers
39 views

How exactly can the hypothetical conformal invariance of the CMB spectrum be established by analyzing tensor modes?

In the introduction of this paper at the top of p11, it is mentioned that a hypothetical enhancement of the scale invariance of the CMB spectrum to conformal invariance could potentially be ...
-1
votes
1answer
79 views

Does science need support from religion or philosophy to explain the creation? [closed]

Science is trying to explain how the universe is made. The beginning of the universe explains the Big Bang theory. But what happened before Big Bang? Science cannot go before that. So, does this mean ...
1
vote
1answer
115 views

Are neutrinos affected by gravity fields?

Am asking if a neutrino can be pull by the gravity field of a quasar or a black hole, assuming the neutrino have momentum. It could be possible in the that a neutrino can orbit a black hole at an ...
3
votes
1answer
44 views

which or what kind of star has a very stable luminosity?

I mean those kind of stars should be very stable and barely have activity. Their light curves should be very very flat. Our sun, as a G type star, are not so stable. At lest there are lots of ...
2
votes
1answer
99 views

In the end what is the ultimate matter/element in the universe, due to fusion process in stars?

We know that, in stars, hydrogen is used by the stars and due to the fusion in two hydrogen elements we get helium -> Carbon -> Oxygen ->Other elements -> Iron -> then Super/Hypernova. If everywhere ...
-1
votes
1answer
47 views

Big Bang Thoery, what triggered it and why [closed]

Given the vast infinite nature of universe, billions of worlds, distances and masses that we cannot comprehend, do you feel Big Bang theory is inadequate and in some ways tells you that it was all ...
2
votes
1answer
64 views

How would Alpha Centauri A appear from the surface of Alpha Centauri Bb?

I'm trying to imagine what a hypothetical observer on the surface of Alpha Centauri Bb would see in the daytime sky. I know it would vary depending on the orbit of b around B, as well as the position ...
0
votes
1answer
29 views

Do contracting objects show redshift?

If we consider a point on the central part of a contracting object as observed from earth, the point is continuously moving away from us as the object contracts. Moreover, light emerges from a deeper ...
5
votes
3answers
126 views

What shape are black holes theorized to be?

I have always been curious about what black holes (or their event horizons) would look like if we could directly observe them. I notice that they tend to be depicted as flat holes in space but it ...
0
votes
1answer
39 views

Sources of astronomy-related dataset?

I'm doing a project for a statistics class, and I thought it may be interesting work with a dataset associated with astronomy. I know absolutely nothing about astronomy, unfortunately, and I wouldn't ...
1
vote
2answers
104 views

How can a Blackhole have mass?

It is said that in Blackhole 100% part of the mass is getting converted into energy. Then how come Blackhole is having mass ?
2
votes
1answer
75 views

Would a Phobos full impact make Mars temporary habitable?

Due to tidal deceleration, Phobos is predicted to be destroyed by Mars in the next 30-50 million years either by collision or by breaking up in a planetary ring. If Phobos falls on Mars in one piece ...
4
votes
1answer
107 views

How small can a planet be and still have Earth-like gravity?

A planet made from denser material than Earth might have equal gravity to Earth but a smaller radius. How small can a planet be and still have Earth gravity? Ideally it should be habitable by humans, ...
6
votes
2answers
1k views

If Earth didn't rotate, would we feel heavier? [closed]

Suppose the Earth's rotation slowed for some reason. Would the lack of centrifugal force cause us to feel heavier than normal? Likewise, if Earth's rotation increased, would we feel lighter as ...
1
vote
1answer
57 views

Why is Mars' atmosphere so thin?

Is it because there isn't life to exhale enough oxygen and carbon dioxide? The size of Mars is about the same as Earth, so isn't there enough gravity to hold enough air?
5
votes
1answer
62 views

Would space-faring vehicles in interstellar space be in pitch darkness, show reflections from the nearest star or be bathed in light completely?

This is not a science fiction question, but I was considering the visual accuracy of ships in space depcicted in Battlestar Galactica and the like. They are always strongly lit. If they are in ...
2
votes
1answer
68 views

Hamiltonian of general three body problem

i try to extend my analysis from planar restricted three body problem to the general one. Is there anyone that can help me to find out the Hamiltonian for this prolem in cartesian coordinates? I ...
2
votes
1answer
25 views

Does Doppler shift affect apparent pulsar frequency?

We know that redshift and blueshift is the result of the frequency of light waves reflected or emitted by an object lengthening or shortening due to the relative velocity of the observer moving away ...

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