1
vote
1answer
72 views

How the watches are showing perfect time?

The actual time for one day is 23hrs, 56mins, 4.1secs right? Then how can the clocks and watches can show perfect time? I mean, if I observe the sun rise at 6:00am this day, tomorrow I should observe ...
1
vote
1answer
273 views

What is the brightest star (by absolute magnitude) that we can see by naked eye?

Is it Rho Cassiopeiae or Mu Sagittarii? I see in the Stellarium 0.13.0 that Mu Sagittarii has absolute magnitude -11.43!!
0
votes
2answers
27 views

Question on Equatorial and Galactic coordinate systems

I'm currently working with proper motions and have needed to convert my galactic longitude and latitude into right ascension and declination (ie from galactic to equatorial coordinates). This is fine ...
2
votes
1answer
65 views

Given a collection of pixels, how to deduce the flux from them?

I've obtained the coordinates of brightest pixels from different images (.fits files) using Python. I want to get the flux of each pixel. How do I go about finding out the flux?
0
votes
1answer
42 views

Why do most meteors vanish just before hitting the ground?

Many times we see in the sky that most of the meteor shower trails vanish when they are about to strike the earth several feet above the ground. Why does this happen? They could strike the earth's ...
2
votes
4answers
278 views

Gravitational wave detection time difference between LIGO Livingston and LIGO Hanford

Quote from LIGO's news release: By looking at the time of arrival of the signals—the detector in Livingston recorded the event 7 milliseconds before the detector in Hanford—scientists can say ...
2
votes
1answer
73 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 ...
1
vote
1answer
54 views

Retrograde motion of planets: reason and time?

I am a beginner. I'd like to understand how planets (except Sun and Moon) exhibit retrograde motion. When does the retrograde motion start for a planet (eg Mars) and how long (time limit) planets ...
3
votes
1answer
35 views

Solar / lunar positions in ECEF using SOFA C libraries

I'd like to calculate the positions of the sun and moon in the ECEF coordinate system using the SOFA (http://www.iausofa.org/current_C.html) libraries given a Julian day input. So far, I've got this ...
0
votes
1answer
72 views

What makes the Moon and Venus shine?

Is there some substance on Venus or some kind of material, because neither bodies have any source of light.
1
vote
2answers
32 views

VLT interferometry vs E-ELT?

If the VLT (very large telescope) can use interferomerty to act as a 200 meter mirror, then why are they trying to build the 39 meter E-ELT? What advantage does the E-ELT have, if the VLT can act as a ...
2
votes
0answers
38 views

Can the expansion of spacetime be directly measured with laser interferometry (like GW can)

LIGO has a mind boggling sensitivity. What would it take to directly measure the expansion of spacetime, along the laser beam? I suppose it could be done at interplanetary scale.
0
votes
1answer
35 views

The relation between the light of full moon and the distance between the sun and the earth

If we want the full moon to be 2 times more bright,how we should change the distance between the sun and the earth? Thanks for your help.
0
votes
2answers
114 views

Far side of the moon question

Do all / most / any other moons orbiting a planet synchronize their rotation so as to become tidally locked with it, or is the earth a special case?
5
votes
3answers
126 views

If a white dwarf collides with a giant star, could it create a TZO?

Thorne–Żytkow objects (TZOs) form from collisions between neutron stars and main sequence or giant stars. Ultimately, the neutron star becomes the "core" of the giant star. However, could this also ...
0
votes
2answers
56 views

What would be the apparent magnitude of Betelgeuse if it were as close to Earth as Sirius?

How large and bright would Betelgeuse appear if it were as close to Earth as Sirius, before and after it goes supernova?
1
vote
1answer
261 views

How to calculate the temperature of a star

I need a way to calculate the effective temperature (surface temperature) of a star for a stellar model. I need something in the form Te=.... I have: Radius in m mass in kg the composition of ...
8
votes
2answers
1k views

Is the earth bombarded equally in all directions by neutrinos?

Perhaps it is hard to known for sure because neutrinos are very difficult to detect, although they do go through the earth in very large numbers. But are they passing through the earth equally from ...
1
vote
1answer
67 views

Telescope choice

Which one is better? Features: 1)Magnification: 18x - 90x Eyepiece Diameter: 5mm (18x), 10mm (60x) Objective Diameter: 50mm Focal Length: 36cm Tripod Height: 38cm Main tube Color: Silver Net ...
-1
votes
1answer
81 views

How do we know that there is no border at the end of “infinite” space? [duplicate]

It has been suggested that space and beyond is infinite, but admittedly the same hypothesis was made by virtue of the fact that it is physically impossible to prove otherwise. How do we know that ...
0
votes
1answer
56 views

Term for altitude of the sun?

The sun travels in an arc across the sky. Where I live, during the summer the arc rises higher, but in the winter the arc is lower. Once might speak of highest altitude or elevation the sun reaches ...
0
votes
2answers
111 views

Question about space-time

In the Big Bang model of the Universe, every observable thing is thought to have expanded very abruptly from a point of infinite density and zero volume. However, the problem with this assertion is ...
0
votes
1answer
27 views

Would a Einstein–Rosen bridge change size and/or position in an expanding Universe?

I appreciate that a Einstein–Rosen bridge has never been observed but since there are some valid theories in General Relativity I thought I'd ask this. Would the start and end point of a ...
-1
votes
1answer
75 views

Explanation for the first spinning neutron star detected in the Andromeda galaxy?

A new class of Neutron stars has been found in the Andromeda galaxy (M31), This is the first time a Spinning Neutron star has ever been detected by astronomers in M31. The article states- “pulsars” ...
1
vote
1answer
82 views

If Venus had moon before and it fell back to Venus, why don't I see a unique, very big crater?

Does lack of a very big crater support the idea that Venus never had big moons before? If not, why can't I find a very big crater from the moon impact?
0
votes
0answers
30 views

How common are Stars that have no orbiting planets? [duplicate]

How common are Stars that have no orbiting planets compared to Stars that do?
9
votes
1answer
1k views

Can dark matter be found in the shape of planets, galaxies etc.?

If dark matter has gravity just like normal matter, does that mean it can also form planets, solar systems and so on? Any answer will be appreciated.
2
votes
4answers
115 views

What planet is better than earth to infer solar system configuration?

The mankind had to work some centuries to infer the real configuration of solar system, starting from greeks, Ptolemeus, until Copernicus, Galilei, Kepler, Newton etc. Is there any planet where we ...
0
votes
2answers
60 views

Are there any studies that prove/disprove the Oscillating Universe Theory?

Is there any evidence that supports or disproves the Oscillating Universe theory? What kind of observations could provide this evidence?
2
votes
2answers
366 views

What are the masses of the two stars (given the information provided)?

If anyone would at least be willing to point me in the direction of finding the answer, or help me solve it I'd appreciate it. I don't know how to go about this, and need to know how to solve this on ...
0
votes
0answers
32 views

Create heatmap from significance

I am working on my project in astrophysics and I would like to create my heatmap from the significance which is obtained by the gaussian fitting my histogram. I get this map : First picture : ...
1
vote
1answer
36 views

K-Pg asteroid impact

Is it possible to determine what daytime the Chicxulub impactor striked the Earth 66 mya? Was it day or night, what was the current phase of the Moon etc.? Can sediments, rhytmites or something else ...
0
votes
2answers
203 views

Is it true that the sun goes down to the west?

I know the sun doesn't go down but we are moving and is it true that the sun goes down to the west? I've read on many webpages that this is not entirely true.
0
votes
0answers
72 views

What was the flash I saw in the night sky?

On Saturday night (April 2nd) in Sydney, Australia, somewhere between 8:30 PM and 9:00 PM my partner and I saw three flashes in the sky. We were looking at Jupiter through a pair of 7x50 binoculars ...
0
votes
1answer
91 views

Two body orbit of equal masses

Given two bodies of equal mass in an elliptical orbit: I know they will be orbiting about a common center of mass, i.e. the barycenter. But, do the velocities have to be equal in magnitude and ...
0
votes
1answer
84 views

Can you see the stars when it is trickling?

I am writing a book with the following scene in one chapter: It is trickling and my protagonists are outside looking into the night sky, looking to the stars. Reviewing the scene I am wondering: Is ...
0
votes
2answers
54 views

Can we tell how fast bodies are moving away by measuring their frequency?

It's clear the universe is expanding because light from distant bodies, like galaxies, are shifted towards the red side of the spectrum. In other words, the light measured is more red than it should ...
0
votes
1answer
83 views

Which class of objects in Solar System carries more mass?

Could you help me sorting this list in terms of total mass carried by these classes of objects? The star (Sun) - it's very big but only one. The planets (incl. dwarf planets). Certainly beaten by ...
0
votes
1answer
35 views

Longitude of the Ecliptic

I originally went to math.stackexchange.com and they suggested I try here as well. I'm trying to figure out how to calculate times of moonrise and moonset for a given position on the earth on a ...
0
votes
0answers
19 views

Magnetic field in blazars

How such high magnetic fields are generated in Blazars? What is the orientation of magnetic field in accretion disc and jets? How magnetic field effects variability? How magnetic field causes shock ...
0
votes
2answers
35 views

How was precision astrometry done before digital imaging?

Did they just put a ruler on the photographic plate? Quite some precision must have been required to discover Neptune from its influence on Uranus for example.
6
votes
2answers
401 views

What can we expect from the first accurate image of a black hole?

From recent news from the Max Planck Institute for Radio Astronomy: The European Research Council (ERC) has awarded 14 Million Euros to a team of European astrophysicists to construct the first ...
0
votes
0answers
34 views

How to create synthetic test images of stars?

Is there any python/IDL code available to create synthetic test images of stars with and without background noise?
10
votes
5answers
618 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.
0
votes
0answers
36 views

Unknown moving objects

Last night, I used my new Sony WX500 camera to get long exposure pictures of the sky from my backyard. I used the "Heavens Above" app to find out when satellite flares would happen, and I even got a ...
0
votes
3answers
63 views

What is the definition of “deep space”?

I need to know the definition of deep space. I am an amateur astronomer, and am experiencing some difficulty understanding this.
3
votes
1answer
61 views

How does an absolute horizon form before the apparent horizon?

If I understand it correctly, the apparent horizon is the boundary between where light directed outwards will move outwards, and light directed outwards will move inwards. Even if light is moving away ...
8
votes
1answer
138 views

Is it possible that Mercury was originally the moon of Venus after a giant impact?

Mercury looks like the Moon, and so it makes me think about a question: is it possible that Venus and Mercury were the a same planet originally, and a giant impact with that planet made it split into ...
1
vote
2answers
50 views

What happens over time as a neutron star cools?

My understanding of a white dwarf star is that, although it hasn't happened yet due to the age of the universe, eventually as it loses energy due to radiating heat and tidal forces, it will cool to ...
0
votes
1answer
35 views

Is nucleosynthesis responsible for the expansion of the universe?

Is it just a coincidence that the two major expansionary periods occur close to periods of nucleosynthesis? Big Bang nucleosynthesis occurred very close to the inflationary period. Supernova and ...

15 30 50 per page