# All Questions

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### How to get from the earth to another planet/ the moon? What happens on the way?

I have a problem explaining for my students how to get from the earth to the moon? Is there someone who can give a good explanation? I Think these are words that might be included. Escape velocity, ...
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### Why can falling stars only be seen moving down towards horizon not up away from horizon?

Are falling stars as we know only just space debris entering and burning up in the atmosphere and not a star at all?
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### Telescope collimation issue

Recently I purchase Chinese 8 inch reflector telescope from local store. When I observing starts and planets I've been having trouble getting really sharp image from this telescope. I observe Venus ...
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### How much heat is generated from waxing and waning of reflected radiation from the Sun?

According to this article, the greatest cause of global warming would be from the waxing and waning of reflected radiation from the Sun. (Placing carbon emissions at 10-20%) So really, how much heat ...
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### Moving from computerised to normal amateur telescope?

A few years ago I purchased a Celestron Nexstar 130 SLT computerised telescope thinking that it would be a perfect to get me into astronomy. The issue is the computer doesn't work at all and manually ...
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### How many constellations in the Zodiac?

Some sources say there are 13 constellations in the Zodiac. Other sources claim there are 12. According to NASA (source): If we count all the traditional constellations, there are 13 in the ...
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### I'm making a presentation for a planetarium, any topic ideas?

As part of a project I'm making a presentation that will be displayed on my university planetarium dome, using the Nightshade software. I'm looking for topic ideas... The subject I thought about ...
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### Calculate Local Sidereal Time

I am trying to follow this guide and move to a programming language but I have doubts. What means the strings A, B and C in this manual? ...
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### How is the Lithium Depletion Boundary used to determine the age of a stellar cluster?

According to my understanding of Soderblom et al. (2014), lithium ages of stars are determined as follows: Determine lithium abundance from equivalent width measurement of Li$_{\mathrm{I}}$ ...
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### How do proto-planetary nebulae gain momentum?

currently I am curious about proto-planetary nebulae. At first I was curious about how planets spin but I read in a couple of articles that they got their spin from when they were in a proto-planetary ...
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### Realistic space environments

You've seen it in all kinds of science fiction, be it books, games, movies, and such. Space is depicted all sorts of ways, with asteroids far too close together, nebula thick enough to hide in and ...
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### What's the bleeding-edge model for how Population III stars are born and evolve?

I'm trying to do a brief literature review to find out what the best current models for population III stellar evolution are. I was hoping that someone with more expertise in the area could perhaps ...
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### What would happen if a rocket traveling at speed of light would collide with a planet (like earth)?

Let's assume it is possible for a spacecraft to travel at the speed of light (I've read the interstellar book by Kip Thorne, apparently this is theoretically possible if you swing around two black ...
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### How special as our solar system compared with other plantary system? [on hold]

For example: Most planets have circular orbit What else?
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### Does liquid water on Mars means life?

We need to figure if liquid water is present throughout a Mars year, and how long the planet has been at its current distance from Sun. That will give us the length of time that liquid water has been ...
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### What would happen if we stepped on the Sun?

I mean in intrinsic detail. What would happen to our bodies besides "burst into flames"?
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### Is liquid water on Mars such a big leap compared with ice?

I thought we have found bacteria or other kinds of life on Mars. Now it is liquid water. Is there such a big difference between liquid water and iced water?
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### Could there be dark matter black holes?

Could dark matter compress and form black holes? Since dark matter is even more abundant than normal matter, a dark matter black hole should not be rare...right?
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### Are planets moving away from the sun?

I saw on the tv show Through the Wormhole (hosted by Morgan Freeman) that the planets in our solar system have been continuously moving away from the sun for millions of years. however, when I try to ...
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### What is the brightest star (relative magnitude) in M31?

I am wondering what the brightest individual star is in M31, the Andromeda Galaxy. Specifically, brightest as seen from Earth (so relative magnitude).
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### Estimation of average rock and asteroid mass associated with different stars

There is a lot of information on different star types and compositions. Can we make estimates of the total mass of rock, ice, and non stellar matter that orbits stars based on star evolution models? ...
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### What are the most valuable meteorites and asteroids in terms of precious metals?

There were some suggestions that asteroids could one day be mined for precious metals. I have found an outdated study that says that some siderites contain as much as 0.001% of gold: ...
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### 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: ...
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### Pyrokinesis? Explain the cause [closed]

-A candle is lit on a table -A 2"1/2 book is placed in front of candle -the candle is obstructed by the book by 3" in each direction except the bottom -I rub my hands together like there cold 4" in ...
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### Can all areas on Earth experience a total solar eclipse?

A solar eclipse only puts part of Earth at a time in shadow, so I'm not talking about a solar eclipse that casts a shadow over all of Earth. What I mean is: are there any areas on Earth where, no ...
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### What light source can cause a shadow of a cloud onto the next cloud above?

Scenario- -Time & Environment-11:00pm Super Moon small town population 40,000 in Central Ca. -Nearest body of water is 80 miles away 4 small lakes of about 1 mile in diameter. -Pacific Ocean is ...
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### How important is the size of an astronaut [migrated]

It seems to me that weight and size would be important in choosing spacefarers for many reasons. I came across this wikipedia article where the Chinese Astronauts have to be between 50 and 70 kg, ...
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### How to calculate the heliocentric velocity of an object?

My task is to calculate the heliocentric velocity of an object to correct for wavelength in a spectrum. I have the RA, Dec and observation date, and I know that the NED velocity correction calculator ...
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### Is our Universe a hologram?

I watched a documentary where I heard some very strange theories that are difficult for me to comprehend. It is even difficult for me to explain what I heard. "Objects that fall into a black hole ...
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### Gaia: What is the difference between CCDs used for astrometry, photometry, and spectroscopy?

My knowledge of CCDs is that these are sensors which collect photoelectrons. That's about it. What is a difference between CCDs used for astrometry, spectroscopy, and photometry? As an example, each ...
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### What kind of signatures can we detect if there is a black hole nearby?

Suppose the sun has a long period companion, it is difficult to detect it? The data precision now can exclude a >>$1M_{\odot}$ black hole, which has a , say, 100 year orbital period with our sun? ...
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### September 26 twelve hours sunrise to sunset?

I noticed in today's newspaper (Boston Globe, September 26) that sunrise and sunset were both at 6:25. That's the twelve hour day I'd have expected at the equinox. (Please retag if there's a better ...
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### Less stars in the night, compared to 15-20 years back

I am not sure if my question is true or not. But this is what I observe regularly. When I was young and when I look at the sky, there were too many many stars were there. But now, from few months I'm ...
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### Should a station in orbit around the Sun travel in the same or the opposite direction to the planets?

If we put a station in orbit around the Sun, and wanted to send transports as regularly as possible without the travel costs being prohibiting; should we have it rotate around the Sun clockwise, or ...
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### Was there ever a Jupiter transit or Saturn transit?

I've watched the Venus transit 2004 with a small telescope, a relatively rare event, considering most people can only observe two in their life time. If E.T. were sitting in a sunny place on a moon ...
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### Spheres in space

I know that gravity will turn a mass into a sphere, which is why planets and stars are that shape. But then we have asteroids and small moons which are not spherical. Such as a couple of Pluto's ...
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### What visual artifacts are expected from the JWST?

What visual artifacts should we expect from the images that will be released from the James Webb Space Telescope? Specifically, do we expect 3-pronged diffraction spikes (any preview how they would ...
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### Understanding Earth Tilt, Sun's Position and Lattitude Calculation

I've been trying to figure out how to calculate the latitude of my location with just the shadow of a stick cast by the sun. I am doing this under the assumption that I am stranded in some place with ...
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### how to asses a pulse amplitude [on hold]

As the figure above shows, how to estimate its pulsation amplitude? Some people use 5.4% rms. What does that mean? Is it necessary we fit a, say, sinusoidal curve in advance?
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### How does light so travel so fast?. [duplicate]

I've read that photon's have zero mass, hence no force is needed to accelerate them. But then the second question. How can gravity affect something which has 0 mass?. Yes, gravity(black hole) can bend ...
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### Could an impact have resurfaced Venus 300 million years ago?

Venus surface isn't older than about 300 million years. The only explanation I've come across is that some kind of global volcanism resurfaced the planet. But couldn't it have been an impact event? A ...
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### Stratospheric Balloon with an Xray camera

Some colleagues and I were planning to launch a stratospheric balloon in December. A thought occurred to me: what if we were to put some sort of xray camera in the payload? We are expecting a maximum ...
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### What is the format of the data from the JPL's HORIZONS system?

I'm looking for accurate positions and velocities of the planets in the solar system over several decades. I want to simulate their trajectories using Newtonian laws of motion, and compare the ...
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### LIfe without an ocean floor on an ocean planet?

Theoretically, wouldn't life need some sort of an ocean floor with irregularities where organic "soups" could "condense"? What about "membranes"? Don't theories suggest that if life came to be near ...
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### Biosignatures for anaerobic or other early microbiology?

What are some possible atmospheric bio-signatures for a planet with anaerobic life? or even microorganisms before oxygen builds up in the atmosphere? Would there be a way of telling if methane, etc. ...
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### When will Sirius be closest to the solar system?

Sirius is currently approaching the solar system, at a rate of 5.5 km/s, consequently in the future it will be closer and therefore brighter. When will Sirius pass closest to the solar system? How far ...
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### Can we know where (South, East, West…) the moon will be at a specific time?

Apparently, a few nights from now (more specifically on the night between the 27th and 28th of September this year, nights being Belgian nights), we will have a lunar eclipse. That's great, and I ...
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### What causes the antipodal bulge?

The Wikipedia article on tides shows a diagram with a tidal bulge both towards the Moon and on the antipodal point (the Sun isn't included in the diagram). Surely that's wrong - what would cause the ...