1
vote
3answers
46 views

How to find RA 0

I am standing in an open area and can see the sky for a full 360 degrees. I have the coordinates of an object (RA and DEC). Where do I look to find RA 0?
1
vote
1answer
33 views

Is starquake unique to neutron star?

I read from somewhere that astronomer use X-ray to observe the "shaking" not to be confused with wobbling of a distant neutron star, I think it is similar to what geologist using microphone to ...
1
vote
2answers
69 views

What triggers solar flares?

The sun is a big ball of hot plasma which contains free electrons. However, how does the absence of metallic elements in the sun generate the magnetic field to orchestrate these free electrons to ...
0
votes
1answer
27 views

Mass resolution

Can someone define mass resolution in terms of cosmological simulations such as the millennium simulation? Is it just the smallest mass that a dark mater particle can have and still be detected by the ...
0
votes
1answer
73 views

Does our sun/solar system orbit around any other celestial objects? [duplicate]

Does our solar system orbit around another massive celestial object? Like a massive star or black hole for instance? From my understanding our sun rotates around the centre of our galaxy, thus our ...
1
vote
2answers
71 views

Why did Venus not lose its atmosphere without magnetic field?

It is often stated that the magnetosphere not only shields the planet from cosmic radiation, but also prevents atmosphere loss. Why did then Venus not lose most of its atmosphere if it doesn't have a ...
0
votes
2answers
51 views

Precessing of the Earth

It's been known that the Earth's axial tilt varies from 22.5 to 24.5. Does this result in a wobbling while the value of the tilt varies about these two limits? If so, how does it affect the mechanics ...
1
vote
1answer
38 views

Shadows of Light = Space or Dark Matter?

Perhaps my title is misleading. but here is my understanding and I'm looking for confirmation. You cannot have dark without light. The only thing faster than light is darkness (i.e. shadows) Stars ...
7
votes
3answers
724 views

How long until we cannot see any stars from other galaxies?

Since all the galaxies are moving further away from each other at a faster and faster rate, eventually we won't be able to see stars from other galaxies. How long until we can't see stars from other ...
1
vote
1answer
29 views

Was the cosmic microwave background (CMB) radiation originally gamma rays?

I believe that sometime after Big Bang the entire universe was filled with high energy particles. Now we fast forward to the present; most of these particles still linger and managed to avoid being ...
2
votes
2answers
333 views

Where does energy at the beginning of a star's lifecycle (before any nuclear reactions) come from?

David Christian's Maps of Time has this to say about the period during which the first stars started to form from the diffuse clouds of hydrogen and helium that then made up the universe: Under ...
0
votes
1answer
44 views

Will the Universe end by time stopping?

I know there are several theories as to how the universe might end, if it does. Is it possible for it to end by time stopping? A friend of mine told me about this theory, but her explanation that it ...
1
vote
1answer
44 views

How do I get from Star Atlas to real life?

This question is about finding the elevation and bearing of a given star at a particular time at Latitude 52N. I look up the RA and Declination of my star. How do I calculate its RA and elevation at ...
7
votes
2answers
317 views

Why are galaxies disk shaped?

I always see galaxies in "disk" shape in pictures. It is like, there is a rotational movement on a plane and the system is balanced by the pulling-in gravitational force which prevents the stars to ...
0
votes
2answers
31 views

How do astronomer measures the size of any celestial objects?

What techniques and tools are available to the astronomers to measure the size of any celestial objects such as, stars or perhaps black holes that doesn't emit light nor reflects starlight?
1
vote
2answers
33 views

How does one measure velocities of far-off, bright objects

As the title already says, I want to know how one measures velocities of far-off, bright objects, e.g. when the mean parallax drift isn't measurable with current apparatus (this means when there is ...
0
votes
1answer
38 views

Do astronomers and astrophysicists more often use diameters or radii when discussing about planets, dwarf planets, exoplanets and stars?

Mathematicians much more often use radii over diameters when discussing about circles and spheres, because in mathematics the radius is more fundamental than the diameter (the sphere is defined using ...
1
vote
1answer
66 views

What came first: the Sun shining or the existence of helium?

This seems to be a chicken and egg problem, the sun begins shining due to hydrogen becoming helium, but it's odd that there was no helium initially without the stars. Is my logic flawed? (Note: ...
0
votes
1answer
50 views

What kinds of technologies are required to directly image exoplanets

I have read that immensley powerful telescopes such as the European Extremley Large Telescope will be able to directly image the atmospheres of exoplanets, and even determine their rotation rates. I ...
3
votes
1answer
94 views

How many arms does the Milky Way galaxy have?

How many arms does the Milky Way galaxy have and how is it determined?
1
vote
1answer
26 views

Simulation packages or theory to work with gravitational collapse of massive molecular clouds?

So, I am getting interested in gravitational collapse of large molecular clouds that fragment and collapse into multiple stars. Are there well-known popular academic simulation packages that simulate ...
1
vote
2answers
60 views

What type of star does theory predict should be the most massive?

The most massive known stars are Wolf-Rayet stars. However, as Wolf-Rayet stars do not appear to be the first stage of any star's lifecycle, I infer that whatever these Wolf-Rayet stars used to be ...
3
votes
0answers
102 views

Why do dark objects look white from a distance? (Moon, Ceres, but not Earth!)

What makes the Moon shine white in the sky, although it seems to be as dark as asphalt? Earth's average albedo is 3 and 4 times that of the Moon and Ceres respectively (0.37 vs 0.12 and 0.09). But ...
0
votes
0answers
43 views

Statistics to prove handedness of the universe

There are some papers discussing a potential handedness of the universe: GalaxyZoo: the large-scale spin statistics of spiral galaxies in the SDSS, Longo with Detection of a Dipole in the Handedness ...
0
votes
1answer
32 views

axial tilt of uranus [duplicate]

Simple question: I read that the axial tilt of Uranus is 97.77 degrees. I don't understand why it would be this instead of 82.23 degrees the other way. It seems like saying that the Earth's axial tilt ...
1
vote
1answer
27 views

What do cosmologists mean when they talk about “the running of the spectral index”?

All I know is that the spectral index is related to the CMB, and that it has to be slightly less than 1 to favor inflation.
4
votes
2answers
147 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.
2
votes
2answers
61 views

Is there a connection between black holes and dark matter/energy?

Is there a spatial or gravitational relationship between black holes and dark matter/energy?
2
votes
3answers
70 views

Is dark energy evenly spaced throughout Universe?

Are there certain parts of the Universe that are expanding faster than others? Is there anyway to definitively measure this?
-1
votes
1answer
35 views

What's the cheapest research-level telescope?

Like the title says, what is the most low-powered (cheapest) research-level telescope there is? Is there any in the consumer price range (e.g. at the cost of a new car)? Of course, scientists probably ...
0
votes
0answers
13 views

LIGO and Fabry–Pérot interferometer

I was currently reading about how LIGO works, it uses the basic principle of a Michelson interferometer, and the laser it uses is infrared laser with 1064nm. so from what I know about interference and ...
2
votes
1answer
67 views

Why does Mars' experience an 'ice age' at high axis obliquity, when Earth experiences an ice age at low axis obliquity

This paper here goes into some detail about how Mars' experiences its own form of 'ice ages' on a quasi periodic basis driven by the wobbling of its axis. The main mechanism outlined is that the ...
0
votes
1answer
48 views

What will the mass of the new galaxy be?

When the Milky Way galaxy collides with the Andromeda galaxy, what will the mass and volume of the new galaxy be?
13
votes
2answers
139 views

Affordable night sky photography

As an amateur with limited budget, I'd be interested in taking photos of the night sky, trying to capture more detail than human eye armed with a lens of comparable parameters to what I have in my ...
1
vote
2answers
119 views

Is it possible that the Sun has a binary partner (the Nemesis Theory) that has eluded detection?

I just recently learned about the theory that our Sun has a small companion star with a 26 million year orbit. This theory came about when it was realized that mass extinction events happened ...
1
vote
2answers
40 views

Could we detect an earth-like planet around another star?

Could we detect an earth-like planet (e.g. similar distance from star, and similar size) with current planet finding techniques? If an earth-like planet were orbiting our nearest star, excluding the ...
1
vote
1answer
29 views

Why do astronomers use supernova to measure distance in space?

Why can't the distances between our Sun and the celestial objects be measured directly and instead had to rely on looking around for supernova? Is these events frequent, evenly distributed and lasting ...
0
votes
1answer
47 views

Why are the high density regions in outer space black holes?

The escape velocity of an object is given by the following formula. $$v_e=\sqrt{\frac{2GM}{r}}=\sqrt{\frac{2 \mu}{r}}= \sqrt{2gr}$$ As far as I am aware, the mass of the star which formed the black ...
0
votes
0answers
8 views

North Pole Right Ascension/Declination to axial tilt conversion

Wikipedia , on several asteroid articles, claims that right ascension and declination of the North Pole can give you the axial tilt of the object. What formula is used to convert these 2 values into ...
1
vote
0answers
42 views

What mechanism could have formed the Moon's Oceanus Procellarum rift-like gravity anomalies?

According to the NASA JPL web-report, Gravity Gradients Frame Oceanus Procellarum, a rift-like ring structure surrounding the Moon's Oceanus Procellarum has been detected as a gravity anomaly by the ...
1
vote
1answer
57 views

Are galaxies moving away from us faster than before?

Are all galaxies moving away from us at constant speed even those that may be moving in our direction as the space is being formed? How does nothingness appear to push matter? A black hole sucks as ...
2
votes
1answer
75 views

The tidal locking problem concerning Earth sized planets in habital 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....oh ok I'm fibbing I can't do it. ...
10
votes
1answer
4k views

How many sun-like stars are there in the universe?

After yesterday's announcement of the Kepler telescope finding a huge amount of newly observed exoplanets, i saw a headline claiming that as much as 22% of sun like stars in the universe have planets ...
1
vote
2answers
33 views

Expansion of Space

If Space is expanding between the Galaxies then why isn't it also expanding between the Stars within the Galaxies as well ? In fact why isn't Space expanding within our Solar System ?
-3
votes
1answer
49 views

Does “Dark Matter” really exist?

Does dark matter really exist or is just a made-up theory in order to cover up the loopholes in the Big Bang theory, and also to explain why universe is expanding at an accelerated rate?
1
vote
1answer
33 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
1answer
59 views

How to calculate the expected surface temperature of a planet

I'm writing a program to generate solar systems but I'm having trouble calculating the expected temperature of a planet. I have found a formula to calculate this, but I haven't been able to get a ...
4
votes
2answers
544 views

What's the mass of the interstellar neighborhood of the Sun?

What's approximatively the mass of the interstellar neighborhood of the Sun ? (for example the neighborhood of radius 50 light-years). Remark: The mass of the observable matter should be completed ...
4
votes
1answer
61 views

Is there any way a planet could form independent of a star?

I just recently heard that there are currently no theoretical models that support planet formation without a star, but I can't remember where. So, I thought I would request all of your expertises. ...
0
votes
0answers
15 views

Orbital resonances and position of planets

I am interested in quick generation of planetary systems for programs similar to Space Engine or Pioneer Space Simulator. As far as I understand, formation of planets is a complex process and the ...

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