5
votes
1answer
34 views

What will eLISA be trying to observe?

eLisa - Evolved Laser Interferometer Space Antenna. A LISA-like mission is designed to directly observe gravitational waves, which are distortions of space-time travelling at the speed of light. ...
33
votes
5answers
4k views

9th planet location?

I've seen a number of news reports indicating there is likely a 9th planet in our Solar System, something with an orbital period of between 10k-20k years, that is 10 times Earth's mass. I haven't seen ...
3
votes
1answer
69 views

Was that actually a shooting star during the supermoon eclipse on September 27th 2015?

During the super-moon total lunar eclipse on September 27th a meteor-like streak passed very close within view of the event. It appeared to happen at the very middle, the maximum eclipse. ...
3
votes
1answer
57 views

Could human life thrive on a planet in a pulsar star system?

Aleksander Wolszczan of Pennsylvania State University found three planets circling a pulsar called PSR B1257+12.Two of the planets were the size of Earth.The pulsar observed by Spitzer, named 4U ...
2
votes
2answers
89 views

Advancement of perihelion, data

I was looking for accurate and up-to-date data regarding the advancement of the perihelion of the planets in the Solar System, the only ones I've found so far are at least 90 years old bout I really ...
1
vote
1answer
52 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 ...
18
votes
3answers
266 views

Is it odd that our Sun has so many planets?

The internet is abuzz with the new evidence of the possible ninth planet in our Solar System. With those nine objects, the asteroid belt, the Kuiper belt, and everything else in our Solar System - the ...
6
votes
2answers
146 views

Ninth planet - what else could it be?

So recently it was announced that there might be a ninth planet out there. Some people (from NASA) say the odds are 50% that it is a real planet, since it hasn't been discovered by telescopes yet. ...
34
votes
3answers
4k views

How many planets are there in this solar system?

So, in school (that's a long time age) they have been teaching us there are 9 planets in our solar system. Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto But every now and then I ...
9
votes
1answer
241 views

How would parallax affect an object at 200-1000 AU (for example, the 9th planet)?

We know from this question that an object is hypothesized to be at between 200-1000 AU that is large enough to detect, known now as the 9th planet. It should move about 40 arcseconds per year. It ...
0
votes
1answer
37 views

What was that Asteroid/Comet in the 90s?

I am now in my mid 20s and I remember when I was 6-10 years old, there was a comet or asteroid that flew really close to earth. I remember being able to see the object very clearly as if it were the ...
0
votes
1answer
39 views

Epsilon Eridani and Sadira

I have seen a number of places on the Internet where Epsilon Eridani is referred to as Sadira. (e.g. https://en.wikipedia.org/wiki/List_of_stars_in_Eridanus ) However, it would seem that its an ...
-2
votes
2answers
75 views

Does the sun itself present the problem of global warming is it the main cause? [closed]

the sun itself is not responsible for global warming, it must be that the temperature is changing due to climate changes. Anyone?
3
votes
0answers
45 views

Redshift for gravitational waves?

According to general relativity, would gravitational waves experience the same sort of redshift that electromagnetic waves experience due to the expansion of the universe? And are there astrophysical ...
1
vote
2answers
836 views

app to locate star by coordinates

I've named a star and would love to be able to find it in the sky - is there an app I can use to locate stars given a specific coordinate?
1
vote
0answers
24 views

Does the quantity of dark matter needed in the Milky Way to give the stars their speed compare with the speed of the Milky Way?

Dark matter was needed to give the stars in a spiral galaxy a cause of their speed. So they proposed there must be some extra dark matter in the Galaxy. The total extra mass of dark mater is quite ...
0
votes
1answer
59 views

Gravity assist: why is the velocity doubled? [closed]

The Wikipedia article has this terrestrial analogy: Imagine standing on a train platform, and throwing a [tennis] ball at 30 km/h toward a train approaching at 50 km/h. The driver of the train sees ...
1
vote
1answer
27 views

Can angular information be known more precisely than the diffraction limit?

The diffraction limit deals with the ability to determine if two things are separate. I am interested in the ability to find the the centroid of a single object. Imagine a star with no near ...
1
vote
1answer
20 views

How to watch at best this week's planet alignement?

I read somewhere that counting from today, five planets will be aligned during almost two weeks IIRC. The planets are : Mars, Jupiter, Saturn, Mercury and... us. I know Jupiter and Mars can be seen ...
1
vote
1answer
54 views

Why there is no axis measurement when telling distance between objects in space ?

What's in upper part in our galaxy ? If space is 3 dimensional, what lies beneath solar system, or in upper part ? Why it seems from every graphical view of solar system / galaxy, everything is in one ...
11
votes
7answers
1k views

Do we know the exact spot where big bang took place?

If you rewind the universe back 14,7 billion years, all matter were in one spot, and then started expanding. Do we know where this is in reference to our own solar system? And is there anything there? ...
1
vote
1answer
62 views

Number of stars & planets in Milky Way Galaxy?

Is there any specific numbers on stars & planets count on Milky Way Galaxy ?
2
votes
1answer
47 views

A beginner project in plotting celestial bodies in 3D coordinate space

As a data visualization task, I'd like to plot some celestial bodies in 3D coordinate space. I assumed there would be a lot of databases where celestial bodies are recorded along with an XYZ ...
-1
votes
0answers
22 views

what is the cause of presence of intense gravity on black hole

As we know black hole has a very high gravity on its singularity why it's so. On what minimum distance the body should present from black hole so that black hole can't affect the body.
14
votes
2answers
2k views

How bright would the sun appear from the hypothetical Planet Nine proposed by Caltech?

Theoretical Planet Nine, proposed by Caltech's Mike Brown and Konstantin Batygin, is said to have a 15-20 thousand year orbit. Approximately how bright would the sun appear from Planet Nine aphelion ...
5
votes
3answers
105 views

On the cosmological principle

Just more of a conceptual question on the mutual inclusivity of the cosmological principle. That is to say, I was wondering if it were possible to have a Universe that were isotropic but NOT ...
9
votes
2answers
433 views

Is there a ninth planet?

After Pluto's demotion as a planet, we have currently eight planets in our solar system. But Sun's gravitational pull can be felt well beyond Pluto, so is it possible to have a ninth planet beyond ...
8
votes
1answer
150 views

Can there be an object with planetary discriminant between Ceres and Neptune?

The planetary discriminant is a measure of how dominant a body is within its region of the solar system. For (true) planets, it is >10000 and for dwarf planets it is <1. See this answer for more ...
0
votes
1answer
30 views

What does the surface of Mercury look like?

What does the surface of Mercury look like? What color is it (I have seen some images portraying it grey and some a light brownish color), and would the surface be dusty like the Moon, smooth, or ...
4
votes
1answer
53 views

We are sure that there are no brown dwarfs closer than ______

I don't quite know how to word this question. How close could a brown dwarf be to us and have gone undetected until now? Or maybe, with what probability are we sure that there is no brown dwarf ...
0
votes
1answer
58 views

The relation of the lit side of the moon and the sun

During different days when both the sun and the moon are seen I notice that the axis of the lit, illuminated, side of the moon does not pass through the sun there is some degree of diversion. Why?
1
vote
2answers
27 views

How does time “add up” for observers outside of and travelers inside of a Krasnikov tube?

A ship travels 99% of c from Earth (leaving at Time A, say 2016) to Destination Star (arriving at Time B, say 2020, accounting for relativistic effects) to stretch the tube, leaves a buoy at ...
0
votes
1answer
29 views

Could the Earth be used to cast an arago/poisson spot on something

There's a potential design for a space-based telescope that uses a large opaque circular disk in place of a transparent lens to focus light for analysis. It uses the light that bends around the disk ...
1
vote
1answer
48 views

how to get image coordinates of source points in saoimage ds9?

I loaded my fits image to saoimage ds9. Then, Analysis->Catalogs automatically brought up source locations. how can i get xy image coordinates of this source locations?
4
votes
2answers
120 views

Is extraterrestrial mining more difficult or impractical for bodies without plate tectonics?

This article talks about the possibility of mining Uranium on the moon. Since the Moon lacks the geological forces that have created veins of concentrated minerals on Earth, would extraterrestrial ...
4
votes
1answer
225 views

What are the azimuths of the planets' orbits?

I am creating a virtual solar system model and I want it to be as realistic as possible (e.g. orbits are ellipses, not circles, and orbits are oriented correctly, not all coplanar). In order for me ...
0
votes
0answers
61 views

Formulas for gravitatitional equilibrium

I am trying to calculate at which point gravitational equilibrium sets in for various bodys (planets stars neutron stars etc.) assuming they are perfect spheres. However the radius i get is not equal ...
1
vote
1answer
54 views

Can dark matter decrease the Jeans length?

I am wondering if there are any models of interstellar cloud collapse out there which take dark matter into account. If dark matter has local perturbations or density fluctuations, then that may be ...
4
votes
1answer
43 views

Why do proto stars on the Hayashi track get dimmer as they contract?

Why do proto stars on the Hayashi track get dimmer as they contract? My expectation is that they would get hotter and brighter the more they contact. Why is this wrong?
0
votes
3answers
108 views

View from inside the black hole

If an observer is falling toward a black hole with its face away from singularity then what will he observe after crossing the event horizon? The reason that why I am asking this question because as ...
2
votes
1answer
111 views

If the Sun got larger, but maintained its luminosity, would the Earth get hotter or colder?

A recent question If the Sun were bigger but colder, Earth would be hotter or colder? asked - if the Sun got bigger and cooler, would the Earth heat up or cool down. I think the answer to that is ...
5
votes
2answers
85 views

Are there ever any simultaneous transits of both Mercury and Venus as seen from the Earth?

Transits of Mercury happen fairly frequently due to its short period, but transits of Venus are less frequent. I've looked over the data available to me and found that there have been transits of ...
1
vote
0answers
88 views

A phonecall inside a blackhole

I was wondering what a phone call would be like entering or falling t=into a black hole. Due to the massive density of the black hole and time would feel slower, how would that appear to the person on ...
1
vote
2answers
116 views

What is the Maximum Speed that can be acheived Because of Acceleration Due to Gravity?

Planets and other bodies in the universe have different ranges of gravitational fields. What is the maximum speed that can be achieved because of acceleration due to gravitational field. In other ...
8
votes
2answers
194 views

Why does this graph for sunlight intensity on land has a steeper slope during sunrise as compared to sunset?

I got this image while checking weather data for a city in North India using Mathematica's Wolfram Alpha query I noticed one feature in the graph which i could not explain . Why does the encircled ...
0
votes
0answers
22 views

Percentage of galaxies rotating with trailing arms

I am looking for the percentage of galaxies that rotate with a trailing arms. I know that only a small percentage of galaxies rotates with leading arms and would like to know whether there are any ...
0
votes
1answer
59 views

Second Big Bang [duplicate]

Just say you are immortal and will live forever. Since the universe is claimed to be unstable, what would happen after it ends? Would all of the universe's mass just fly back into another compressed ...
1
vote
4answers
95 views

What do we mean by Sunrise and Sunset?

If the Earth rotates on its own axis, then what do we mean by sunrise and sunset?
2
votes
1answer
114 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 bearing and ...
1
vote
0answers
19 views

Which moons have cold traps? (i.e. low ecliptic inclination in orbital and rotational axes)

Both the Moon and Mercury have polar cold traps in polar craters, with signs of volatiles. This is of course not as interesting on a moon in the outer Solar System which consists of volatiles anyway. ...

15 30 50 per page