All Questions

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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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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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Are stars NML Cygni, UY Scuti, VY Canis Majoris and VV Cephei near the ends of their lives?

Are the four stars mentioned in the title stars that are going to go supernova, or are they stars that are in mid-life, like our Sun, but just happen to be so much larger than our Sun?
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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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Were parts of the Universe deflating during Inflation?

I was reading about the history of the early universe in Carroll & Ostlie and specifically looking at Inflation, which, as I understand, occurred because our [observable] part of the universe ...
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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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the metal distribution in our solar system

The sun dominates in our solar system. I wonder whether in every aspect the sun plays the most important role in our system. For example, all kinds of metals are mainly located in the sun instead of ...
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When a neutron star accretes matter, will its mass increase?

When a nova gets matter, the outcome is that it may lose more matter because of eruptions. Only some kind of nova's masses can increase stably. A white dwarf may become a supernova after it exceeds ...
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What will happen to life on Earth when the Andromeda and Milky Way galaxies collide?

It is said that the Andromeda and Milky Way galaxies are coming close to each other with a speed of approximately 400000 km/hour. They will be together in the next 4 billion years. What will happen ...
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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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Will Saturn's rings become a moon?

Planets form from disks of matter orbiting around a star; some moons form from disks of matter orbiting planets. If this were going to happen around Saturn, approximately how much time would it take?
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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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Does any iron fuse in stars before they go supernova?

I understand that iron and all heavier elements consume more energy to produce than they make, and that is what eventually leads to a supernova. I also understand that a lot of the heavier elements ...
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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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Blowing up an asteroid/comet really potentially worse?

Often on television shows and in articles I see it mentioned that it'd always be bad to blow up an asteroid or comet because then the energy would just be spread out and cause even more damage. ...
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What uncertainty does an error bar signify in astronomy?

When an astronomer talks about her/his topic and shows an X/Y-plot with error bars. What should one assume that those error bars represent? 1 standard deviation? Or 2? Or some specific significance ...
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Why does the darkening of the Moon go from left-to-right during an eclipse?

In anticipation of the upcoming April 2014 lunar eclipse, I decided to use the 3D virtual planetarium software Stellarium to simulate what it is supposed look like where I live, since I've never ...
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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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Why there are other planets in our solar system? [closed]

Earth receives sunlight from Sun; in a similar way, do we receive any kind of energy from other planets? My question is: We are dependent on sunlight, which is energy from Sun; similarly, are we ...
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Eternally collapsing objects?

As has been pointed out by some scientists, that black holes aren't stable bodies but are eternally collapsing objects. How does one come to such a conclusion? Is hawking radiation related to this in ...
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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 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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Is expanding universe adding potential energy?

A system with two massive bodies has potential energy proportional to their separation. Since the universe is expanding, is the potential (and total?) energy of such a system slowly increasing? What ...
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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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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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Image sets for testing stacking algorithms?

I am looking for sets of astronomical images for testing different kinds of stacking algorithms. The idea is simple: if one has $N$ images of the same object, the signal-to-noise ratio of the ...
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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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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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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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Why is the Solar Helical (Vortex) model wrong?

Could someone give a lay description of why the Solar System's depiction of motion as a vortex is wrong? ref: Youtube video The helical model - our solar system is a vortex Please don't take for ...
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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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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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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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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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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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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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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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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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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 ...
116 views

Where exactly does the Moon flip, given that it appears the other way up in the other hemisphere?

I've read in multiple sources that the Moon appears the other way up in Northern Hemisphere vs Southern Hemisphere. Here is one that explains why: Does the Moon look different in the northern and ...
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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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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 ...