5
votes
1answer
185 views

Lack of planets in the Oort Cloud

With the current news about the possibility of a planet in the Oort cloud, I was thinking, why is the matter in the Oort cloud distributed so? It makes sense that inside the planet region there is not ...
3
votes
0answers
28 views

How to find the distance between two quasars

I want to calculate the distance between two quasars of which I know the angular position and the red shift. Let $Q_1=(\alpha_1,\delta_1, z_1)$ and $Q_2=(\alpha 2,\delta 2, z_2)$ and suppose $z_2 > ...
2
votes
1answer
133 views

Can a supernova make a new star? [duplicate]

Today I was wondering with a friend about the birth of a star. So we know that stars are born from a nebula, but the residue of a dead star (like a supernova) is itself a nebula. So can a star be born ...
1
vote
2answers
66 views

Calculating the mass of star

I am doing a project which requires that I have data for the mass of several stars. However, the data for mass of stars is obviously not readily available as it's really hard to calculate. In such a ...
4
votes
1answer
84 views

Speed of blast from supernova

How fast does the blast front of a supernova expand at? Is it close to the speed of light or is it less than a quarter of the speed of light?
4
votes
1answer
114 views

Could an ejected “extra ice-giant” still be lurking in distant solar orbit?

BACKGROUND Hot Jupiters are thought to have migrated inwards, implying that another giant planet has been ejected in order to conserve the orbital momentum of those planetary systems. The number of ...
0
votes
0answers
17 views

How will the Breakthrough Initiatives affect other astronomy observations?

BACKGROUND The Breakthrough Initiatives is in the news because of a $100 million private donation for a SETI project. It doesn't seem to be for building any new observatory (but maybe for buying ...
2
votes
1answer
85 views

Can a galaxy splits into multiple galaxies?

Is there any naturally occurring event powerful enough that can cause a galaxy regardless of shape and size to divide itself into two or more smaller galaxies?
2
votes
1answer
429 views

Shall we say now that Pluto is “larger than Mercury” ?

http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20150717-3 "Scientists working with NASA’s New Horizons spacecraft have observed Pluto’s atmosphere as far as 1,000 miles (1,600 kilometers) ...
1
vote
1answer
77 views

How significant is a planet's density to the formation of life?

I'm doing some writing set on a fictional earthlike planet that for reasons needs to be substantially larger than Earth but can't have substantially higher gravity. I've been able to compromise with a ...
2
votes
2answers
125 views

about H$_\alpha$ and H$_\beta$ lines in astronomical objects' spectra

Generally there may be some line ratio between the two lines. If H$\alpha$ is strong, it is quite possible we can see H$_\beta$ too. Is it possible we can see H$_\beta$, but can not see H$_\alpha$? ...
2
votes
2answers
98 views

Was the Universe expanding before the beginning of inflation?

My point of view is that first there was the Big Bang singularity, and then the period of inflation which resulted in the observable Universe becoming many times bigger. But was the Universe expanding ...
1
vote
1answer
51 views

Why do we observe spectral lines of specific energy?

The basis of my confusion is that atomic orbitals, even when described accurately by quantum numbers, have definite energies, meaning they represent energy eigenstates of the wave function. They're ...
11
votes
2answers
421 views

How do we know Milky Way is a 'barred' spiral galaxy?

In reference to the question, "How can we tell that the milky way is a spiral galaxy?" The answers there clearly sum up the question asked. But Milky Way is not just a spiral galaxy. It is further ...
3
votes
0answers
60 views

Is the Tombaugh Regio on Pluto visible from Earth?

Is the Tombaugh Regio on Pluto discernably visible from Earth ground based or Earth orbiting telescopes? And more generally, can surface features seen in Hubble images be matched with images from New ...
6
votes
3answers
236 views

Why are radio telescopes shaped so differently than optical telescopes?

Why are radio telescopes typically only a dish with a receiver above it, while optical telescopes have a primary, plus secondary and sometimes even a tertiary mirror? In other words, why do radio ...
3
votes
1answer
135 views

Real images (not “artist concept”) by NASA

Does NASA make publicly available real images of missions in an organized manner? What I mean is: Say I'm looking for the images taken by New Horizons - a simple list of the images in chronological ...
4
votes
1answer
92 views

which pulsar has the longest spin period so far?

Vela X-1 has a 283s spin period, while this one may have a 2.7hr spin period. However neither of them is included in ATNF catalog. They are not included in $p-\dot{p}$ diagram either. The longest ...
0
votes
1answer
106 views

How can they tell no asteriods will hit earth in the next hundreds years?

It has come to my mind this interrogation : How can they tell no asteroids (big enough to create damage) will hit earth in the next hundreds years? Because, so far, we were unable to get a clear ...
2
votes
2answers
47 views

How many nested stable (1 Mio years) orbits are theoretically possible?

If we look at our solar system we have the sun which has planet orbits and planets have moon orbits. If we look at the possible size difference from hypergiants to small asteroids why shouldn't it be ...
5
votes
2answers
131 views

Official Definition of Satellite?

So I had an argument with a friend, which was about whether the Moon is a planet or a satellite. IAU 2006 Resolution B5 gives definitions on what it is to be a planet, but there is a vagueness, as I ...
4
votes
1answer
48 views

Speed of light through the ISM and Wavelength

Articles written about fast radio bursts describe the signal's short-wavelength components arriving before its longer-wavelength components, suggesting energy-dependent time delays in the interstellar ...
4
votes
0answers
97 views

Why are retrograde orbits more stable than prograde ones?

Regarding solar system dynamics, i.e. planets in stellar systems and moons in planetary systems, this is often mentioned in the literature, but it is difficult to find a good analysis/explanation of ...
3
votes
2answers
192 views

Can stellar black holes cancel each other?

Hypothetical question: when a pair of identical stellar black holes are very close to one another wouldn't the side facing each other experience lower gravitational force? How is this logic un/sound?
1
vote
1answer
123 views

Planets and moons positions in cartesian coordinates?

Is there freely available and reliable source, where one can find positions of planets and moons of the Solar system at given time in cartesian coordinates? (I am writing a simple gravity simulator ...
0
votes
1answer
89 views

Is the Universe really expanding at an increasing rate?

Here's what I just read from Wikipedia's page on the Hubble Space Telescope: While Hubble helped to refine estimates of the age of the universe, it also cast doubt on theories about its future. ...
8
votes
3answers
3k views

If Venus and Mars changed places, would we then have 3 habitable planets?

This is the supposition: Venus is too hot, Mars is too cold. If they switched places then Solar energy would change to make both more Earth like. We might as well have had three instead of just one ...
3
votes
1answer
78 views

Which kind of properties can we get for cosmic ray particles hitting on an optical ccd?

It is very common that we meet cosmic ray particles in optical images recorded by CCDs. You can see the "snowflakes" in the hubble images below: Generally we should remove them in order to get ...
1
vote
0answers
78 views

Energy required for light speed [closed]

It is said that in order for us to travel at the speed of light, there has to be an infinite amount of energy. Light is made up of photons but photons themselves do not have an infinite amount of ...
18
votes
2answers
1k views

Can you see man-made lights on the dark side of the Earth from the surface of the moon with the naked eye?

This question is prompted from a comment on this answer: Could a person on the surface of the moon see man-made lights on the dark side of the Earth with the naked eye? If not, how much magnification ...
2
votes
1answer
38 views

How significant and accessible is modern Chinese astronomy?

Is China fully integrated in the international astronomical community, or does military secrecy and language problems and sanctions (ITAR) or something else stand in the way? Does China have valuable ...
4
votes
2answers
81 views

Is there a mechanism that makes small moons more rounded than comets?

67P/Churyumov–Gerasimenko has a highly irregular dumbbell shape. But the sample of comet shapes observed is very small, so I wonder if irregular shape is the norm for comets and for small moons. Many ...
0
votes
1answer
428 views

what planet is the most radioactive?

So as I understand it the source of most geothermal energy on Earth is due to radioactive decay. Jupiter is the most massive planet but if the bulk of it's mass comes from gaseous elements instead of ...
7
votes
2answers
581 views

Visibility of Apollo 11 module

I wasn't around when man landed on the moon in 1969. When I see the moon, I always wonder, were people able to see the rocket? Yesterday, I looked at the moon in daylight and wondered again. My ...
7
votes
2answers
3k views

Why don't we see the galaxy center?

When we look at the sky, and see the Milky Way, we mainly see a band, with no real center. On a more accurate picture we can guess the center of the galaxy (see this picture), but we still don't see ...
1
vote
1answer
61 views

Who invented the blink comparator?

The Wikipedia page for the blink comparator fails to mention who invented it. Many other pages extol the importance of the device, but we cannot find any mention of an inventor. Wikipedia does ...
4
votes
3answers
500 views

What would the night sky look like if Earth orbited an intergalactic star?

If the Earth and its host star were located exactly in-between the Milky Way and Andromeda would the night sky be completely void of light? Would stars be visible to the unaided eye? So there could ...
2
votes
1answer
135 views

What will the last days of Earth be like?

The sun is a main-sequence star; as I understand it the sun will expand into a red giant in a few billion years. I have heard conflicting reports of what this entails - some sources I found say the ...
6
votes
1answer
145 views

Will the Sun rotate slower in red giant form?

When the Sun runs out of hydrogen to fuse it will grow bigger in size and my question is does it rotate more slowly, like a spinning ice skater extending their arms to reduce angular velocity? What ...
3
votes
3answers
553 views

Appropriate battery for overnight viewing to drive telescope and GOTO?

I have a Plettstone 18" Dobsonian telescope with GOTO and clock drive that runs off a 12 volt cigarette lighter adapter. What is an appropriate battery to use to run this overnight while viewing all ...
5
votes
1answer
343 views

How long until the Earth and Moon become a binary planet?

With the rate at which the moon is further receding into a higher orbit, how long until the barycentre between us and the moon leaves the earth, and going by the IAUs 2006 definition update, we become ...
4
votes
0answers
39 views

Are trojans in L5 more likely than in L4?

Mars has much more trojans in L5. Does it reflect a common pattern?
1
vote
1answer
47 views

Suns Orbital speed and escape velocity question

This is a homework question and I don't want an answer but just want to understand what its asking for. We are given that a star with a mass of x solar masses in ...
6
votes
4answers
694 views

Can magnetism escape a black hole?

I know light, and practically nothing but gravity can escape a black hole. My question is: can magnetism escape a black hole? A couple things that convince me it can are: Jupiter's magnetic ...
2
votes
0answers
31 views

Semimajor axis variations in co-orbital moons

I've been playing with simulations of co-orbital bodies similar to Saturn's moons Janus & Epimetheus- horseshoe orbits where the two bodies are of comparable mass- and I'm seeing some very odd ...
4
votes
1answer
89 views

Radio Astronomy and Imaging

So, I've been starting to investigate radio astronomy, and am wondering about if certain things are possible from an amateur standpoint. I was looking at this powerpoint(that discusses building a tiny ...
2
votes
2answers
97 views

How clearly would I be able to see a galaxy with the naked eye if viewed from a “close” distance?

In images of other galaxies they look very bright and vivid against the blackness of space (example). If I was located a few tens of thousands of lightyears away from a galaxy, would I see something ...
1
vote
1answer
58 views

How far away would a supernucleus comet be visible?

If an instrument like LSST quickly spots something as soon as it reaches magnitude 24½, how far away would a 60km first-time visitor from the Oort cloud be when it is spotted? I'm thinking that a ...
2
votes
1answer
52 views

Could martian meteorites come from Olympus Mons?

Could Olympus Mons have thrown ejecta out of Mars' orbit when it was active? Does it fit with the composition and dating of meteorites with martian origin?
2
votes
1answer
82 views

What is the ratio of cosmic microwave background radiation to normal radiation?

I would like to know the ratio of cosmic microwave background radiation to normal radiation in the universe. I am considering cosmic microwave background radiation to include the microwave, and any ...

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