1
vote
2answers
60 views

Delta-v from Mercury surface to Venus surface

What it says on the tin: using the most efficient launch opportunity afforded by orbital mechanics, what delta-v would you have to impart to a payload to send it from the surface of Mercury to crash ...
5
votes
1answer
171 views

How can one explain the apparent motion of the Sun from a heliocentric point of view?

From a horizontal frame of reference, the path of the Sun looks like a part of a circle in a tilted plane, as shown in this picture: ...
4
votes
1answer
83 views

How did Batygin estimate when Planet Nine was ejected?

Konstantin Batygin has estimated that if Planet Nine was ejected, it would have been ejected 3-10 million years after the formation of the Solar System. I'm curious as to how he arrived at this ...
1
vote
2answers
152 views

Will a Ball placed close to Sun fall into it?

Like a ball falls on the earth due to gravity, if suppose we are able to place a ball close enough to the sun. Will the ball fall into the sun due to its gravity or will it be pushed away due to its ...
4
votes
0answers
45 views

Oldest Reference to Astronomical Seeing

I'm writing a paper on astronomical seeing. Sir Isaac Newton identified both the phenomenon and origin of astronomical seeing in his Opticks. He writes: ...
1
vote
0answers
22 views

Public Data Set on Atmospheric Absorbtion / Extinction

Is there a publicly available data set for mean atmospheric absorption / extinction? I would like to be able to process and plot a graph similar to this image from NASA on wiki commons. The HITRAN ...
7
votes
1answer
88 views

Could the trajectories of non-periodic comets be used to infer properties of the 'ninth planet'?

Non-periodic comets are comets which have very long orbital periods (>200 years or more), spending most of their time in the outer solar system. Planet X, recently revived by researchers at Caltech, ...
1
vote
1answer
31 views

Planets classification by density

In our Solar system, the density of major planets varies from 0.7 g/cm3 (Saturn) to 5.5 g/cm3 (Earth). For exoplanets, the density varies from very low (0.03 g/cm3 for Kepler-51x) to very high (77.7 ...
1
vote
3answers
103 views

If sun steals comets from other stars, then what is the primary source of comets?

I heard some theory that sun may steal materials such as comets from neighbouring stars, is it true? But if is true, what is the primary source of those comets? Especially "who" creates them instead ...
5
votes
1answer
105 views

What good evidence exists for the 9th planet as spoken of by Caltech?

I'm sure Caltech has answered this in some way, but I think it's a good question have on this site. What good evidence exists for the 9th planet as spoken of by Caltech? As I see it, Caltech has ...
10
votes
2answers
250 views

Hypothetical beyond Neptune far away planets orbiting the Sun

The planet HD 106906 b was found at 650 AU from its home star, which is not a star much different from the Sun. Fomalhaut b is also a young planet that is orbiting very far away from its sun. These ...
3
votes
1answer
99 views
6
votes
2answers
224 views

Can we conclude with reasonable certainty that there is/are no Type 3 Civilizations in our galaxy?

As per the Kardashev Scale, type-3 civilizations are defined as "civilization(s) in possession of energy on the scale of its own galaxy, with energy consumption at ~ 4 x 10^44 erg/sec". Considering ...
5
votes
1answer
83 views

Do planets migrate suddenly or gradually?

Current models of the configurations of the planets conclude that Neptune once migrated outwards. AFAIK this refurbishment came about by Jupiter and Saturn gradually getting into and leaving a ...
3
votes
1answer
88 views

How were the orbits of planets first mapped out?

I'd like to know how the orbits of planets were first 'mapped out' and to understand the maths behind it. e.g. How do we know what position in space a planet will be at certain time so that spacecraft ...
0
votes
0answers
18 views

Has celestial navigation been materially impacted by the imperfect nature of celestial reference frames over time?

In this video on inertial reference frames, it is mentioned that the stars are humanity's best inertial reference frame: the earth experiences a subtle acceleration relative to the sun due to the ...
12
votes
3answers
1k views

What wavelength to best detect the “9th planet”?

We know that the reflected sunlight will make detecting the 9th planet very difficult in the visible light. Is there another band that will be more likely to detect it? What is the surface temperature ...
3
votes
1answer
181 views

Are there good animations of the movement of proximate stars over long time periods?

After reading about Barnard's Star and how it's approaching us 140 km/sec, I'm curious if there are any visualizations of how the nearest stars to Sol will be moving over the next 100k years or so. ...
0
votes
2answers
52 views

Why would discovering life on another planet be important/matter to us?

I had a funny thought, and would like to pose it to you: When I was a kid, reading any kind of astronomy or similar books would all say that there was no other life in the universe, and made it ...
-2
votes
1answer
40 views

The big bang and our expanding universe

The Hubble telescope can see the light from the big bang.My question is if our universe is expanding that would make everything that's in front of our solar system be in the future? And also can ...
14
votes
2answers
382 views

How long should it take for us to observationally determine if Caltech's Planet Nine is really there?

Caltech just released a report that says there is possibly a large (10 earth mass) planet in a remote orbit (10 - 20 thousand year) that explains a lot of observations of Kuiper Belt objects. How long ...
3
votes
1answer
77 views

What type of planetary-mass object would Planet Nine be?

Given that Planet Nine is hypothesized to be 10-20 times the mass of the Earth orbiting the sun some 200-2500 AU out, what kind of planetary-mass object would it be? Even given that it has apparently ...
6
votes
1answer
154 views

How was the hypothetical ninth planet kicked so far out of the Solar System?

I was reading this article on science news and ran into the following statement: Such a remote super-Earth probably originated closer to the sun only to be kicked out by the other giant planets ...
0
votes
1answer
37 views

Why is it so difficult to discover the earth Trojan?

It is discovered only in 2011. Why is it so late? We know where to find it.
3
votes
1answer
56 views

How can the Kuiper belt coexist with the 9th planet?

There are asteroid belts, and there are collections of bodies in resonant orbits, such as Trojans. Aren't these separate things? The recent evidence for the 9th planet is an alignment in various ...
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
68 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
50 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
265 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
144 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
240 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
37 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
72 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
39 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
824 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
19 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
53 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
61 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
46 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 ...

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