# All Questions

116 views

### Is antimatter also attracted by gravitational field?

As we all know matter is attracted by the gravitational field of black hole. So, my question is: Is there any possibility of a black-hole attracting antimatter? Can you explain how/why please?
67 views

### Can a probe orbit Pluto given Charon's gravity?

Is it possible for a man-made probe to orbit Pluto given its closeness to Charon? The gravitational field interaction of Pluto and Charon is likely to make simple orbit structure difficult for a ...
34 views

### Can New Horizons probe turn back and start orbiting Pluto

New Horizons probe has found astonishing features on Pluto, while the likelihood of making even greater discoveries is remote in further space. Is it possible for New Horizons probe to turn back and ...
140 views

### Size of Sun as seen on Pluto

What would be the size of Sun as seen from surface of Pluto? It obviously depends on the distance and one would expect it to be very small. However, due to different optical phenomenon, the size of ...
60 views

### My question relates to KIC 8462852. What are the orbits and suspected objects or planets that have been noted around this star?

What are the orbits and suspected objects or planets that have been noted around this star? KIC 8462852
14 views

### What is meant by “short lived” in the duration of a planetary nebula?

In this wikipedia article, it describes planetary nebula as "short-lived," but I'm not sure in relation to what? This could mean billions of years in some contexts. How long is short-lived? Bonus ...
81 views

### Conversion of matter into antimatter

Is it possible that the intense gravity of a black hole converts matter into antimatter? Does this mean that matter or energy that goes inside the black hole is converted to antimatter?
38 views

### What is projected separation and how can I make sense of its unit (h^-1 kpc)?

I have been reading this paper on the separation of a binary quasar in which it states: At a projected separation of 8.3/h kpc (Omega_matter = 1), CTQ 839 would be the smallest projected ...
31 views

### relation between azimuth angle of the sun and angle of the shodow

What is the relation between azimuth angle of the sun the bearing of an vertical object's shadow? For example if the bearing of the shadow is 75° can we conclude that azimuth angle of the sun is ...
201 views

### Can a solar flare destroy every electronic item on earth?

I was reading a book about the sun which suggested that a solar flare can destroy every electronic item on Earth. Is this really true and if so, how would it happen? Could we do anything to to prevent ...
26 views

### In what units to quote the thermal Blackbody temperature

Just a quick question relating to the thermal Blackbody temperature of a celestial object. In the c.g.s regime of astrophysics, is it more 'sophisticated' to quote the thermal Blackbody temperature in ...
176 views

### How is it that all planets (and moons) in our solar system are in equilibrium orbits?

Previously, I was told that in order for any bodies to orbit each other for over a long period of time, the orbital period, distance and masses have to be precisely matched such that the bodies won't ...
51 views

### Questions about terminology used for Mars and its moons

I am having difficulty with some terminology: sub-Martian hemisphere of Deimos ... what place on Deimos does it refer to? leading/trailing apex of Phobos ... what place are those? Apex ... in ...
80 views

### Super moon or Super lag? [closed]

On Sep 25 2015 in California, at 8pm the moon was observed between 11 o'clock and 12 o'clock position in the sky. On Sep 26 at 8pm at the same location the moon appeared roughly between 11 o' clock ...
247 views

### Why don't these Clouds show no depth perception in correspondence to the Sun [closed]

The pictures show exactly what my naked eye visualized.What is the cause of this?
54 views

### Does 2 merging black holes necessarily make a quasar?

2 black holes are about to merge to become a larger black hole. Does this mean it'll become a quasar? From what I know, quasars are supermassive black holes or a collective amount of them. So, if it ...
166 views

### If quasars are powered by black holes, why are they so bright?

If a black hole can swallow everything, even light, then how can a black hole power anything, particularly something as bright as a quasar. Why doesn't the black hole swallow the light of the quasar? ...
67 views

### Are all models of ocean planets theoretically cloud covered?

Take for example an ocean planet slightly smaller than the Earth. Let's say it has a planet-wide ocean that is on the average 10 miles deep. Say for argument sake, that there is a molten, rotating ...
89 views

### Moon's negative greenhouse effect?

Using the standard formula for effective temperature of a planet, Venus has T(eff)=220K, Earth has T(eff)=255K and Mars has T(eff)=212K (using albedo for Venus a=0.7, Earth a=0.367, Mars a=0.25). ...
125 views

### Is there a web service providing orbital data of solar bodies (planets, comets, asteroids, dwarf planets)?

I would like to be able to connect to a web-service and retrieve JSON data containing information on current (as of today or so) orbits of planets, comets, asteroids, and dwarf planets in our solar ...
87 views

### Finding a location using the direction of shadow, UT and date approximately

Does anyone know how to find a location by using : the direction of shadow relative to the normal (for example azimuth angle) the Universal time (UT) and date I have a satellite image and I know ...
60 views

### Is Ceres a terrestrial-type (dwarf) planet?

Does Ceres belong to the terrestrial-type celestial bodies?
164 views

### Is ours the first universe?

I see here that after a very long time into the future, "Estimated time for random quantum fluctuations to generate a new Big Bang". This begs the question, do we speculate that our big bang was the ...
136 views

### Successor to the Hubble Telescope

Are there any plans for the 'Hubble2'? Maybe with an even bigger mirror capable of even finer resolution, to look even deeper into the origins of the universe? If so, when can we expect to see it in ...
71 views

### Why are the magnetic poles of a pulsar so far off the rotational axis, yet stable?

My understanding is that a pulsar is a neutron star whose magnetic poles don't coincide with the rotational poles and whose magnetic poles sweep through Earth (allowing us to hear radio noise). If we ...
269 views

### Disc of the milky way

For those that haven't seen this link - please have a look as it's a an awe-inspiring 360 interactive panormic image of the milky way (may need a bit of time to load though!). I've found myself idly ...
260 views

### If we found evidence of life on Mars, how would we know that it originated on Mars rather than Earth?

Consider this scenario. One of the probes sent to Mars either very soon, or within the next century, finds conclusive micro-fossil evidence that life once existed on Mars. One theory today that is ...
161 views

### Brightest star of the night sky

I read in many astronomy sites that Sirius is the brightest star of the night sky and that Orion’s Belt points to Sirius. For some days I have been regularly watching Orion (just before dawn) but the ...
105 views

### Can we see the past image of Earth because of curving light by massive objects?

I know massive objects can curve light, can we capture the image of past Earth by lights from Earth that curved by massive objects?
224 views

### What constellation does sun occupy by location and date?

How can i find the location of the sun and which constellation it would occupy based on the location and date of year. for example: an observer is in Des Moines, Iowa on April 10th, which ...
87 views

### Existence of multiple universe?

In this youtube video, Prof. Michio Kaku mentions there could be multiple universes and if there are, then there could be a worm hole to some other universe. My question is: We are not sure if the ...
36 views

### From Mean Moon to True Moon in an old procedural calendar

This is a follow-up to How to interpret this old degree notation? It is about an old calendar system which generates a luni-solar calendar with a procedural method, using a handful of calculations ...
65 views

### Can you see pleiades and sirius at the same time on the sky?

I am would like to know if you can see pleiades and sirius on the sky at the same time from Greece? What time of the year would that be? And I would be very greatful if someone knows some interactive ...
125 views

### What happens when two black holes collide? [duplicate]

There are many hypothesis saying that there will a collision between the milky way and Andromeda galaxy...so what happens when two black holes will collide?? And how will it effect the other objects ...
39 views

### How would the explosion and fallout of a nuclear bomb on the moon compare to one on earth?

What effects would the atmospheric and gravitational differences between the earth and the moon have on a nuclear bomb explosion and fallout?
57 views

### Eclipses of Jupiter's Moon during Retrograde motion

When Jupiter is undergoing retrograde motion as seen from the Earth, would you expect the eclipses of Jupiter’s moons to occur several minutes early, several minutes late, or neither? Can someone ...
57 views

### Double Planet Orbiting Wide Binary Star?

Right now I'm writing a sci-fi story that develops in a double planet. But that's not all, the double planet (along with a couple more planets) orbit a big star and the whole system is orbited by ...
866 views

### If a person were to die on the Moon or Mars, would the body decompose?

There wouldn't be enough oxygen for any bacteria to decompose the body, right? Not to mention, the radiation of space might kill off most organisms on it. So would it decompose, given millions of ...
145 views

### Why is metallicity important in the death of stars?

I always thought that mass was the sole determinant of a star's fate. Then I saw the table here. So why does metallicity influence a star's ability to become a black hole or neutron star? Does it have ...
20 views

### dataset of stars in the milky way galaxy [duplicate]

Does anyone have any idea were I can get a dataset of stars in the milky way galaxy, their mass and their planets and distance of planets from their star? I have tried various catalogs of NASA. I ...
96 views

### How does gradual crossing over of the Roche limit transform a planet or moon?

Some cartoon simulations (an example) of an object (assume here a large moon with Earth-like density) which crosses the Roche limit of a much more massive giant planet, illustrate a circle suddenly ...
109 views

### Luminosity Schechter function for galaxies

Just a question I am having trouble understanding. I have the Schechter luminosity function for galaxies, given as: ...
50 views

### Low precision GMST formula clarification

According to the website http://aa.usno.navy.mil/faq/docs/GAST.php, a low-precision way of calculating the GMST is via the following formula: GMST = 18.697374558 + 24.06570982441908 D The website ...
79 views

### Distribution of Stars in Milky Way and globular cluster analogy

Just a quick (and hopefully simple) question on the distribution of stars in the Milky Way and in globular clusters. I was wondering why it IS NOT possible to describe the distributions of stars in ...
28 views

### How does gyrochronology deal with differential rotation and axial tilt?

K2 seems to become an even better mission than what a continuation of Kepler would have been, at least to some astronomers. By what means is differential star rotation being dealt with? The rotational ...
85 views

### Definition question: continuum-subtracted spectrum

What is the exact definition of a "continuum-subtracted spectrum", such that one finds in SDSS spectra? http://classic.sdss.org/dr7/dm/flatFiles/spSpec.html#specmask Is there a definition ...
99 views

### Could Pluto and Charon have extra-Solar origin?

Pluto and Charon seem to have surprisingly young surfaces, considering that resurfacing events were expected to be rare for them. Could the explanation be that they actually are young? Formed later ...
59 views

### What places on Pluto and Charon are facing each other?

What places on Pluto and Charon are facing each other? Are Pluto and Charon perfectly tidally locked, or is there a slow rotation over time? And how long after formation should they have become ...