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1answer
75 views

“Juxtapositions” of moon,stars and planets in the sky,

What are "Juxtapositions" of the Moon, stars and planets called? When the Moon, stars and planets take exactly the same position after few or many years, how to describe the positions and what is ...
0
votes
0answers
41 views

When exactly star Sirius shines into the queen's chamber of Great Pyramid?

I read that Great Pyramid was built to resonate with Sirius by aligning an airshaft that connected to queen's chamber. That is, the light of Sirius going through the shaft would be able to shine into ...
0
votes
0answers
52 views

Saw 8 stars moving in same direction one by one [duplicate]

I saw 8 stars moving in the same direction one by one and then at the same point they faded or you can say disappear. The speed was not too fast but not too slow either. I am more curious because ...
1
vote
1answer
36 views

How can I check if we can observe a certain star (given its equatorial coordinates) from a certain location on Earth (given its DMS coordinates)?

I am given the equatorial coordinates of a star (e.g. Sirius has RA: 6h45m8.9s and Dec = -16°42'52.1"). Now my question is: can we observe this star from a specific location on Earth (e.g. from ...
2
votes
1answer
53 views

How much does the stellar radius change if seen through different filters?

I know that the radius of a star should be different depending on the filter being used to do the observation. That is, the bluer the filter, the smaller the measured stellar radius. I know this ...
5
votes
3answers
200 views

How do we know distant stars still exist

The Pleiades are 450 light years away. Thus when we see the twinkle in the night sky the light that hits our retina emanates from the year 1569 or so. On that proviso; how can we be sure that the star ...
0
votes
1answer
86 views

What area of Proxima Centauri would need to be occluded for the effect to be observable on Earth?

One of ideas of how Breakthrough Starshot could communicate data from Proxima Centauri is to have a massive swarm of the solar sail powered craft to pivot (with their sails) synchronously, taking ...
5
votes
3answers
650 views

Why do stars twinkle but planets don't [duplicate]

Many people say that stars twinkle because of Earth's atmosphere. However, the atmosphere is still there when we look at planets and don't see they twinkling. Is there a clear scientific consensual ...
1
vote
3answers
66 views

Ratios of magnitudes instead of differences

The color index in the photometric system is defined by the differences in magnitudes between two wavelength filters, which gives the ratio of intensities. For example, to determine the B-V index, you'...
7
votes
1answer
380 views

Why is H_delta prominent in type A stars?

I understand factually that H$\delta$ lines are most prominent in type A stars and less so in more extreme types of stars on the H-R diagram. However I was wondering the reason for why they are not ...
4
votes
1answer
167 views

What is equation of straight line for a ideal blackbody on the color color diagram?

The color-color diagram is a plot between $U-B$ vs $B-V$ values. For a ideal blackbody, what is the equation of this line? In other words, what does the linear relation between $U-B$ and $B-V$ look ...
4
votes
1answer
106 views

How do we measure the mass of a star?

I recently came across the book intro to cosmology by j.v. Narlikar, where it mentions about quarks and other star and inadvertently uses mass of sun as reference. I want to know how me measure mass ...
1
vote
2answers
220 views

Fraction of circumpolar stars to all stars visible in a location

We know that circumpolar stars are stars that don't rise or set. If we are in a location with $\phi = 35^o N$. What is the fraction of circumpolar stars to all stars visible in this location? I know ...
0
votes
2answers
126 views

When were the horizontal and equatorial celestial coordinate systems invented?

When were the Alt-az system and the RA-dec system first used?
1
vote
1answer
102 views

Do objects that are invisible to the naked eye occlude much of the stars to Earth based observers?

I was looking at a star recently and some other object that appeared to be stationary in relation to the star was occluding the light to only one of my eyes. This is why it caught my attention. I was ...
1
vote
1answer
567 views

Stellar parallax

I am doing a project on "how astronomers measure distance" where i came about with stellar parallax. i realized how it works with trigonometry but i am having a slight doubt tan p=distance between ...
2
votes
0answers
79 views

Where can I find raw text, ascii, or binary data from the GALEX satellite?

I am looking for stars in the GALEX data through the GALEX data using GALEXview and plugging in their Henry Draper Numbers http://galex.stsci.edu/galexview/ But the task is tedious by hand. Is there ...
1
vote
1answer
104 views

Percentage of charted stars

I was reading Gene Roddenberry's guide for TNG writers and he mentions that that the time of ST:TOS, only 4% of the stars in our galaxy have been charted; this goes up to 19% by the time of TNG. This ...
4
votes
1answer
222 views

Could non-supernova carbon, oxygen, or silicon flashes be observed?

I was reading about the helium flash, the short but sudden onset of helium fusion in certain red giant stars. As I understand, the upper (nondegenerate) layers of the star absorb the energy as they ...
4
votes
1answer
110 views

Why the light curve goes down when the planet is behind the star?

There is a video explaing the transiting exoplanet light curve — https://www.youtube.com/watch?v=RrusIZaWDW8 It is clear to my why the curve goes down when the planet is between the observer and the ...
2
votes
0answers
103 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?
5
votes
1answer
624 views

Why when we look through a telescope in space, do the billions of stars not block our view from seeing further?

I know that we are able to "see back into time" by looking very far away through telescopes such as the Hubble telescope, but my question is, wouldn't you run into at least a couple of stars that were ...
14
votes
4answers
6k views

How Would a Neutron Star Actually Appear?

Having seen many pictures produced by artists of neutron stars and planets that orbit some of them, I was wondering how a pulsar would appear to a human being, in visible light (assuming the intense ...
1
vote
1answer
968 views

Calculate Dec and RA of a star from Euler angles and GPS data

I have 9DOF sensor (accelerometer, gyroscope, and magnetometer) that gives orientation via Euler angles (yaw, pitch, roll). Along with GPS data (latitude, longitude, elevation, time) this is passed to ...
3
votes
1answer
51 views

Standard conditions for a heliacal rising

I imagine there are several possible conditions for determining the time of a helical rising of a star, the elevation of the star at sunrise, the latitude of the observer, and the azimuth of the star. ...
1
vote
2answers
261 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 ...
3
votes
1answer
156 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 ...
1
vote
3answers
1k views

Could there be a closer star to Earth than the Alpha Centauri triple star system, excluding the Sun? [duplicate]

Do we know for certain that the nearest star to Earth, excluding the Sun and the theorized Nemesis, is the Alpha Centauri multiple star system, at +/-4.4 light-years away? Have we been able to ...
8
votes
1answer
239 views

How often are new astronomical objects (variable stars, supernovae, comets, etc) discovered by amateurs?

How often are new astronomical objects (variable stars, supernovae, comets, etc) discovered by amateurs? Where could one report new findings?
6
votes
2answers
191 views

How can we know the nature of the companion in a neutron star binary?

The companion of a neutron star could be a main sequence star, white dwarf, neutron star or black hole. We detected a pulsar-pulsar binary several decades ago. But if one of the pulsar does not ...
9
votes
1answer
800 views

If we were to see the Sun with our naked eyes from the Orion belt, would all planets be encompassed inside the star? Is this calculable?

When we see a star it looks much bigger in diameter to us than it really is, this picture (extracted from here) explains what I mean: Notice that the point we see in the skynight, represented by the ...
3
votes
2answers
7k views

How to calculate Longitude from Right Ascension?

Considering that a star of certain declination is crossing the local meridian at the observer's zenith at an unknown location on the earth. Here, the declination of the star is equal to the observer's ...