13
votes
2answers
146 views

What earth organisms would survive if they arrived on Mars?

Contaminating other planets is a concern in space exploration. My question is what organisms, or small collections of organisms, from earth would be able form a self-sustaining population on Mars? I'm ...
1
vote
0answers
69 views

How to get the longitude of the perihelion to find the Heliocentric Equatorial coordinates of a planet

I'm writing a program to randomly generate star systems and I have been having a difficult time figuring this out. I've found the equations I need to get the heliocentric equatorial coordinates, but I ...
6
votes
3answers
4k views

How long does a sunrise or sunset take?

From the time that the sun appears on the horizon, or meets it on its setting, to the time that it is fully visible, or no longer visible on its setting, how much time passes? Secondly, is there a ...
1
vote
2answers
140 views

Can earth escape sun's gravity with the help of a black hole heading towards our solar system?

To escape the Sun's gravity, the Earth would need sufficient amount of energy. Let's say a stellar black hole has entered our solar system and at a certain distance from earth, the black hole exerts ...
3
votes
2answers
159 views

Does spacetime return to being flat?

I wrote an experiment in HTML5 and Javascript to try to show what is happening to the curvature of spacetime as a body moves through a region. As time progresses, I'm using the ...
2
votes
1answer
95 views

Does gravity bend light, and how much time does it take for light to cross gravity of a Black Hole?

This is very confusing to me, so the question might be same. Please go through it, if required i will add more text. According to Einstein's theory of general relativity, photons are not technically ...
4
votes
1answer
78 views

How to cool down a moon?

I'm doing an Astronomy project and need to terraform a moon. It is about the size of Mars and orbits a gas giant which is at a distance of 1.28 AU of its star. I though about putting a sunshade at the ...
1
vote
1answer
67 views

Space Travel and length of time [closed]

So I read that if an astronaut travels at the speed of light and goes to a nearby star system , when he or she returns, he or she will have aged 10 years but 1000 years will have gone by on Earth. ...
1
vote
1answer
99 views

Understanding gravity

Forgive me if my question has an obvious answer, but I need to know the answer. I always thought that more massive/energetic objects had a stronger force of gravity than less massive ones; that is, ...
14
votes
6answers
3k views

Are we still going to have rainbows if Sun is replaced by another star?

Rainbow is a property of light splitting due to the water molecule present in the clouds and is related to the light emitted by our Sun. Our sun is a yellow star. Now if we replace sun by a blue giant ...
3
votes
1answer
57 views

Formation of our Universe

So I got this information from a magazine , Scientific American issue Physics at the Limits. The theory is that our Universe came about, when in the "Bulk Universe", which is four dimensional, a four ...
2
votes
1answer
33 views

Looking for an equation that describes how star (x,y,z) positions are affected by expanding universe

I understand that coordinates of stars are in RA,DEC. I am looking for a mathematical expression that describes how the positions of stars change due to the expanding universe.
10
votes
3answers
3k views

What if Earth and Moon revolved around each other like Pluto and Charon?

What would be different for us if Earth and Moon revolved around each other like Pluto and Charon do?
2
votes
1answer
33 views

In a binary star system, what relation determines the eccentricity of the three orbits (for $m_1$, $m_2$, and the reduced mass)?

In a binary star system, why does $$e_1 = e_2 = e$$ where $e_1$,$e_2$, and $e$ are the eccentricities of the three orbits of $m_1$,$m_2$, and the reduced mass, respectively.
1
vote
1answer
50 views

Why don't the stars in a binary star system of equal masses always orbit their center of mass in a circular orbit?

If I have a binary object system of equal masses, why don't they always have the same circular orbit around their center of mass, like in the photo?
-1
votes
2answers
58 views

What types of meteorites can I use for making a wedding ring? [closed]

I want to buy some meteorite and put stones made from it into gold or platinum ring. Or maybe I can use some metal meteorite for making ring? What kinds of meteorites can I use? It must be strong, non ...
15
votes
2answers
2k views

How many planets have we discovered that can support human life?

I have heard a lot of buzz about distant planets that could potentially be second homes for human existence, but what is that approximate number?
4
votes
1answer
156 views

Two black holes photo interpretation

Please see this image: I wonder two things about these black holes. The first is, what are the oblong, smaller black hole-looking voids outside the perimeter of the major black holes? Also, why are ...
6
votes
1answer
132 views

How to tell a pulsar is rotation-powered or accretion-powered?

We need to calculate P/Pdot? A pulsar may switch between theses two states. For a rotation powered pulsar, it can pulse and, the pulsed Lx can be much larger than the luminosity given by its ...
2
votes
1answer
40 views

Quasars and Gamma Ray Bursts

Has there been any study to suggest that either quasars of gamma ray bursts are more detectable from further distances in the universe? I've read that quasars are the most powerful energy in the ...
3
votes
1answer
234 views

Is there any real evidence to prove or disprove the existence of alien civilizations?

Is there any real proof that alien civilizations exist in outer space? What if someone were to say that Earth is the only inhabited planet in the whole universe? How would you respond? I need to ...
1
vote
1answer
91 views

What's the relation between Einstein's Gravitational Theory and Dark Matter?

I was reading an elementary book on dark matter (in fact, a historical perspective) and there were mentioned how the scientific community react to the idea of dark matter proposed as a solution to ...
1
vote
2answers
95 views

Betelgeuse and sun classification

In this video, between 4 and 6 minutes, the lecturer describes M type stars as being less massive, smaller, and redder than G type stars. He then gives Betelgeuse as an example of an M type star and ...
1
vote
3answers
263 views

Oldest in the universe

When the big bang happened and all that exist today came into existence from singularity, how do you determine which part of the universe is the oldest? Its natural to think that looking back at the ...
4
votes
1answer
95 views

The contents of potential “message” in the Wow! signal lost?

The Wow! signal is still an enigma. I understand the incredibly high signal strength it entails. This during some time-period because the sweep of the alignment (or rather the receiving station). ...
1
vote
2answers
65 views

Can the centripetal force be inverted? [closed]

Using the centripetal force to create artificial gravity has been proposed for space exploration. From our perspective, the force is an outward force, pushing objects away. Could it be inverted to ...
0
votes
1answer
28 views

How does one reference the Hubble constant?

I want to use the current value for the Hubble constant 73.8 km/s/Mpc in a paper. How do I reference this value?
2
votes
1answer
85 views

When is it a good aproximation to consider a star to be an ideal gas?

I am currently taking a first course on stellar astrophysics, and I noticed that in some cases we use the ideal gas equation of state for stars, so we also use $\gamma =5/3$. Of course it can only be ...
4
votes
1answer
111 views

Why would the Earth's solar analemma would be still a figue eight even if Earth's orbit was circular?

The Earth's solar analemma is a diagram showing the deviation of the Sun from its mean motion in the sky, as viewed from a fixed location on the Earth. ... For [a planet] with a circular orbit but ...
1
vote
1answer
60 views

What is the illuminance of Tau Ceti?

As part of my physics project, I investigated the relationship between a light bulb's illuminance and the distance from the measuring device to it. Illuminance was measured in flux, and distance in ...
4
votes
1answer
83 views

How do you estimate the error on the height/width of a Gaussian?

I'm trying to fit Gaussians to several lines in a spectrum that I have. Some of them overlap with one another, causing the fitting program that I'm using to not be able to give reasonable estimates ...
4
votes
1answer
111 views

Why does Saturn have both moons and rings?

From my understanding, a ring can form around a planet when a moon gets too close to its Roche limit, and gets ripped appart by the planet's gravity pull. That makes sense to me, but I don't ...
4
votes
1answer
56 views

What is an “arc” spectrum ?

I sometimes hear about astronomers using an arc spectrum to calibrate observations. For example a "He-Ar arc spectrum". What is an "arc" in this context? I assume it's nothing got to do with angles (...
2
votes
1answer
70 views

Name for 1-e and 1+e terms?

In several equations of orbital elements (such as the determination of true anomaly from mean anomaly), the terms 1-e and 1+e appear. These are the ratios of the orbital periapsis and apoapsis to the ...
7
votes
1answer
72 views

What is the composition of an asteroid in percentages?

I am developing a RPG game (or so I like to tell myself) within outer space. Within the game, players would be able to mine small asteroids and collect resources, in order to make money. I'm having ...
2
votes
1answer
44 views

What does an Einstein-De Sitter universe look like?

I know an Einstein-De Sitter universe is a "flat" universe, i.e. with a K ("bendiness", sorry, don't really know what to call it in English) factor of 0, but does that entail anything as to its ...
4
votes
1answer
127 views

Simulate an orbit with orbital elements

I want to simulate the orbits of the planets from our solar system. I want to use orbital elements to calculate the current position(xyz) at a time t. The simulation doesn't have to be too exact, but ...
4
votes
1answer
55 views

Rings around a smaller, close-in planet?

Is it possible for a small, close-to-star planet to have a stable ring system--icy or otherwise? A smaller planet means the rings would have to be closer to the planet, which means the radial shear (...
4
votes
1answer
100 views

Ambiguity in Earth's “Tilt”

It’s well-known that the axial tilt of the Earth (with respect to the ecliptic) is about 23.4 degrees. However, two angles is needed to specify the orientation of any rigid body, so it’s unclear to me ...
3
votes
1answer
356 views

Why do certain massive stars leave no remnants?

Mass and metallicity are the two main determinants for a star's fate. This is simple enough. What's more complicated is how exactly these determine the star's fate. For example, you can see in this ...
7
votes
1answer
196 views

Are we sure there are no planets inside Mercury's orbit?

Currently, most explorations about new planets are pointing to area outside Neptune's orbit, but how about inside Mercury orbit? Can we say for certain there are no planets inside Mercury's orbit?
2
votes
1answer
145 views

Can a star orbit around multiple planets or a planet with massive moons?

Note: I'm not talking about a star orbiting around a single or lonely planet :) I know a star orbiting a planet is almost impossible because if a planet is more massive than a star, that "planet" ...
4
votes
1answer
115 views

How many stars are in the Sculptor Dwarf Galaxy?

The Sculptor Dwarf Galaxy is a small satellite Galaxy of the Milky Way. There are many such satellites galaxies and I'm trying to compile basic data on them. However, I can't find an estimate for the ...
1
vote
0answers
51 views

Stellarium script star of bethlehem

Does anyone out there have a script to replicate the star of Bethlehem. In this case meaning a conjunction of Venus and Jupiter near Regulus.
0
votes
2answers
83 views

Can quantum entanglement cause nucleosynthesis to happen in stars?

Even if there isn't enough heat and energy in the star to cause nucleosynthesis, could atoms quantum entangle to create a new atomic nuclei? Or would it be quantum tunneling - if this is possible?
3
votes
1answer
128 views

Can we simulate Earth's gravity in space?

Earth gravity is 9.8 $ms^{-2}$ Gravity on ISS(international space station) is 8.2 $ms^{-2}$ approx. As per this http://physics.stackexchange.com/questions/29929/gravity-on-the-international-space-...
2
votes
2answers
99 views

Alignment of Semi-Major Axis of Orbits

So I'd like to ask whether the semi-major axis of planetary orbits are aligned? Logically, they shouldn't be, but many websites act as if they are. If they're not aligned, what's the angle between the ...
4
votes
1answer
70 views

Are high-speed galactic collisions survivable?

This is a hypothetical question, but it really is meant as a vivid way of asking about the affects of high-speed galactic collisions. The November 27 APOD showed the Cheshire Cat galaxy group, and the ...
4
votes
1answer
56 views

How (un)stable are the Lagrangian points 1, 2 and 3?

A couple questions, please: I know that the Lagrangian points 1, 2 and 3 are unstable and special Lissajous orbits plus some station-keeping are required to place a spacecraft around them. But I was ...
4
votes
2answers
180 views

Software to convert RA and DEC into ALT and AZ

I have implemented the formulas to convert AR and Dec into altitude and Azimuth in C++ following the book Practical Astronomy with your Calculator or Spreadsheet 4th Edition. In the book there is an ...

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