2
votes
2answers
233 views

What does Stephen Hawking mean by 'an infinite universe'?

In the recent $100m search for extra terrestrial life project project, Stephen Hawking is quoted in the following way: "We believe that life arose spontaneously on Earth," Hawking said at Monday's ...
1
vote
0answers
17 views

How can exoplanet moons be detected? [duplicate]

How can exoplanet moons be detected? Are there current methods to differentiate exoplanets with moons and exoplanets without moons? Or, are only the combined masses of the exoplanet and its moons ...
5
votes
1answer
71 views

Why do some artificial satellites decrease and increase in brightness multiple times?

I just observed a satellite almost directly above me travel for a few minutes while constantly dimming and then getting brighter. It did this for about 3 minutes until it faded out. I also observed a ...
3
votes
1answer
55 views

About the reference for equation of state

Well, I am a post graduate studying mathematics. Current I am working on the mathematical theory of star(not an expert thought). When I am making some assumption on the equation of state (for a star ...
-1
votes
1answer
55 views

What would Earthlike planets bigger than Earth with <10 m/s^2 gravity and complex life be like? [closed]

Large is bigger than Earth. Assuming that such planets exist (though I guess if such planets don't exist that would explain much of the Fermi paradox). Maybe some amount of iron is needed though, to ...
0
votes
1answer
42 views

If your near a black hole and your time is slowed down, would a supernova be observable to both you and someone outside of the blackhole's pull?

Let's say that Person A is on a planet orbiting a blackhole(Like the one from interstellar) and time is slowed for Person A. Person B is back home on Earth. Now let's say a supernova happens and it's ...
2
votes
2answers
66 views

Galaxy Cluster Temperature

I've read once in an article that the temperature of the medium between the galaxy superclusters is extremely high. What does that temperature really mean? particles' velocity? Why is that so? Is ...
5
votes
1answer
236 views

Are there any Stars we know don't have planets?

We have been looking for planets around other stars for a while (see related Are there any other Earth-like planets in the universe? ) and we are finding lots of planets, some of them are Earth like ...
6
votes
1answer
363 views

why does pluto have a high orbital inclination

Pluto has a high orbital inclination compared to the planets in our solar system. What has caused Pluto to have such a different orbit -- was it always like this, or did something happen to make it ...
3
votes
0answers
36 views

Linear motion in the equatorial frame

I would like to calculate how the RA/Dec changes when an object has an apparent linear motionin the equatorial sphere. For example, more or less what an artificial satellite would do in a circular ...
3
votes
3answers
347 views

During night on the Moon is there Earth light and Earth phases?

I realise that night time on the Moon is two weeks, however I am curious if during the night there, whether or not the Earth reflects light in similar manner to the Moon. On the one hand, I know it ...
4
votes
1answer
125 views

First time visit to dark sky stargazing site: what do I need?

Complete newbie here. I have an opportunity to visit one of the few designated dark sky sites here in Pennsylvania, Cherry Springs State Park. I plan on camping out over night, but I have never gone ...
8
votes
1answer
69 views

How to find the distance between two quasars

I want to calculate the distance between two quasars of which I know the angular position and the red shift. Let $Q_1=(\alpha_1,\delta_1, z_1)$ and $Q_2=(\alpha 2,\delta 2, z_2)$ and suppose $z_2 > ...
4
votes
2answers
91 views

Massive Nearby Stars

Is there a possibility that I will find records of stars with masses around 25-30 solar masses within 30 parsecs of solar system. If not, how far do I need to look?
8
votes
1answer
178 views

Pluto- Current theories regarding its geological nature?

The images of New Horizons from Pluto will take more a year to arrive from space, for the moment with have some compressed images as a preview. Nasa has advanced some information regarding the ...
1
vote
2answers
76 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 ...
4
votes
1answer
96 views

Speed of blast from supernova

How fast does the blast front of a supernova expand at? Is it close to the speed of light or is it less than a quarter of the speed of light?
2
votes
1answer
198 views

Can a supernova make a new star? [duplicate]

Today I was wondering with a friend about the birth of a star. So we know that stars are born from a nebula, but the residue of a dead star (like a supernova) is itself a nebula. So can a star be born ...
3
votes
0answers
59 views

Any freely available large stellar spectra catalog?

For a non-astronomy personal project I would like to have a large set of optical stellar spectra combined with absolute magnitude when available. I search for a dataset that contains 10k - 10M objects,...
1
vote
1answer
64 views

Has SETI data been used for astrophysics? How, or why not?

SETI collects alot of data from space, mostly radio. I wonder if this data has any astrophysics value other than SETI?
0
votes
0answers
19 views

How will the Breakthrough Initiatives affect other astronomy observations?

BACKGROUND The Breakthrough Initiatives is in the news because of a $100 million private donation for a SETI project. It doesn't seem to be for building any new observatory (but maybe for buying ...
2
votes
1answer
89 views

Can a galaxy splits into multiple galaxies?

Is there any naturally occurring event powerful enough that can cause a galaxy regardless of shape and size to divide itself into two or more smaller galaxies?
4
votes
1answer
128 views

Could an ejected “extra ice-giant” still be lurking in distant solar orbit?

BACKGROUND Hot Jupiters are thought to have migrated inwards, implying that another giant planet has been ejected in order to conserve the orbital momentum of those planetary systems. The number of ...
2
votes
1answer
135 views

Can we see Earth by looking into space?

It is known that spacetime is curved,so I am wandering to know if its possible to look into space and we see earth (light from earth long long ago). Did I understood spacetime correctly and if its ...
2
votes
1answer
525 views

Shall we say now that Pluto is “larger than Mercury” ?

http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20150717-3 "Scientists working with NASA’s New Horizons spacecraft have observed Pluto’s atmosphere as far as 1,000 miles (1,600 kilometers) ...
1
vote
1answer
60 views

Why do we observe spectral lines of specific energy?

The basis of my confusion is that atomic orbitals, even when described accurately by quantum numbers, have definite energies, meaning they represent energy eigenstates of the wave function. They're ...
3
votes
1answer
94 views

Is the Tombaugh Regio on Pluto visible from Earth?

Is the Tombaugh Regio on Pluto discernably visible from Earth ground based or Earth orbiting telescopes? And more generally, can surface features seen in Hubble images be matched with images from New ...
1
vote
1answer
91 views

Are lunar occultations visible to the naked eye?

The Moon occults a lot of stars. But are these events visible to the naked eye? Won't it be blinded out by the crescent even at its thinnest just before sunrise? Did ancient astronomers actually ...
1
vote
2answers
154 views

What is a “jumping trojan”? And what do their orbits look like?

I was googling Neptune's trojan companions and found on Wiki this claim about ~200 km diameter (316179) 2010 EN65: " the object is actually a jumping trojan, is jumping from the Lagrangian ...
5
votes
2answers
481 views

Does Pluto have impact craters?

I've heard from a lot of sources that Pluto doesn't seem to have any impact craters, but I see a few things that look like impact craters, highlighted in this picture: For comparison, here's ...
1
vote
1answer
90 views

How significant is a planet's density to the formation of life?

I'm doing some writing set on a fictional earthlike planet that for reasons needs to be substantially larger than Earth but can't have substantially higher gravity. I've been able to compromise with a ...
5
votes
3answers
655 views

How did our ancestors discover the Solar System?

I wonder, how did our ancestors discover the Solar System? They did not have any telescopes to see distant objects, right? Even a planet looks like a star from a distance. They discovered the ...
4
votes
1answer
104 views

What's to be gained from the New Horizons mission once it's beyond the Kuiper Belt?

Now that we have seen what Pluto has to offer and New Horizons is headed to the Kuiper Belt, is there anything we can gain from the mission in interstellar space after it travels beyond the Kuiper ...
2
votes
1answer
67 views

How do you determine which star, between two, is more luminous?

For example, if star 1 is 4x bigger than star 2 but both are the exact same temperature how do you determine which is more luminous?
3
votes
1answer
137 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 ...
2
votes
1answer
79 views

Any tip on maintaining a log of celestial objects?

I am an amateur observer and Olympus 10x50 binocular is my tool. As I keep locating celestial objects (Planets, Stars etc), I would like to maintain a log of the observed objects. The purpose of the ...
0
votes
2answers
168 views

How can they tell no asteriods will hit earth in the next hundreds years?

I have been thinking about this question : How can they tell no asteroids (big enough to create damage) will hit earth in the next few hundred years? Because, so far, we were unable to get a ...
2
votes
2answers
48 views

How many nested stable (1 Mio years) orbits are theoretically possible?

If we look at our solar system we have the sun which has planet orbits and planets have moon orbits. If we look at the possible size difference from hypergiants to small asteroids why shouldn't it be ...
5
votes
1answer
107 views

which pulsar has the longest spin period so far?

Vela X-1 has a 283s spin period, while this one may have a 2.7hr spin period. However neither of them is included in ATNF catalog. They are not included in $p-\dot{p}$ diagram either. The longest ...
4
votes
1answer
52 views

Speed of light through the ISM and Wavelength

Articles written about fast radio bursts describe the signal's short-wavelength components arriving before its longer-wavelength components, suggesting energy-dependent time delays in the interstellar ...
7
votes
0answers
143 views

Why are retrograde orbits more stable than prograde ones?

Regarding solar system dynamics, i.e. planets in stellar systems and moons in planetary systems, this is often mentioned in the literature, but it is difficult to find a good analysis/explanation of ...
3
votes
2answers
244 views

Can stellar black holes cancel each other?

Hypothetical question: when a pair of identical stellar black holes are very close to one another wouldn't the side facing each other experience lower gravitational force? How is this logic un/sound?
6
votes
2answers
157 views

Official Definition of Satellite?

So I had an argument with a friend, which was about whether the Moon is a planet or a satellite. IAU 2006 Resolution B5 gives definitions on what it is to be a planet, but there is a vagueness, as I ...
3
votes
1answer
80 views

Problem with Dobsonian reflector telescope

I'm not sure whether I should ask this question here but I'll give it a shot. I have a XT8 Dobsonian Reflector telescope and it works fine. But recently when I use the focuser to focus the image when ...
3
votes
2answers
1k views

How to calculate the moon phase [duplicate]

I need a way of to calculate the moon phase. Do you know resources for research the theory from behind this? I basically have searched in Google, but the results were not very satisfactory. Exists a ...
1
vote
1answer
212 views

Planets and moons positions in cartesian coordinates?

Is there freely available and reliable source, where one can find positions of planets and moons of the Solar system at given time in cartesian coordinates? (I am writing a simple gravity simulator ...
0
votes
2answers
55 views

Historical astronomical lunar tables

I hope this is the right place to ask this question, and I apologise if not. I've come across a date written in an old book, but it is written using what seems to be a lunar/zodiac system. Below is a ...
1
vote
0answers
88 views

Energy required for light speed [closed]

It is said that in order for us to travel at the speed of light, there has to be an infinite amount of energy. Light is made up of photons but photons themselves do not have an infinite amount of ...
11
votes
1answer
805 views

Is there a limit to how hot a star can be?

I think that size and mass do not correlate to temperature, but then again these factors contribute to the internal pressure. I would like to know if there is a limit to how hot a star can get and ...
2
votes
2answers
638 views

How to calculate a planet's current position within the solar system

I'm making an application that needs to calculate a planet's current position within the solar system - I don't want to calculate its position in the sky. For example, what I want to do is exactly ...

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