# All Questions

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### Variables in the Instability Strip

I was thinking about the possibility of determining what phase of evolution a variable star is in when it is located in the instability strip (say, a Cepheid object). Can you differentiate whether it ...
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### Where is Mars in the night sky

I live around Houston, Texas and I'm taking advantage of Earth hour to look at the stars. I've found two objects that I think might be Mars. Both of them are in roughly the same plane as Venus and ...
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### Proof that Parallel Universes exist

Today I heard on the radio that the Super Collider has discovered mini black holes. They said that this discovery is proof of the existence of Parallel Universes and that the "Big Bang" never ...
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### How do you calculate the lookback time distance to a given galaxy?

By lookback time distance I mean the same as Light travel distance. Can you calculate it by just knowing its redshift?
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Stars can easily fuse atoms to give of heat and radiation. But at Wikipedia it said that only sub-iron atoms give of energy when fused and take energy when split, and post-iron atoms is the exact ...
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### Does the sun have a feature like the red spot on Jupiter?

Does the sun have a feature or prominence like the red spot on Jupiter? Is there a feature that will remain as long as the red spot? Maybe beneath the surface?
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### Could someone see anything while being inside black hole?

If we managed to survive in a black hole and move inside the event horizon then could we see the surroundings of the black hole inside the event horizon by source of light? Can the light not come up ...
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### Recombination question and arrow of time

Before recombination was there any present, past or future since photons were "trapped" and couldn't make that measurement possible?
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### Help identifiying a Diagram

Has anyone ever seen a similar diagram? I overlapped this image onto another and some of the lines line up. I'm trying to find a pattern that fits this. Sorry if this isn't the place for this ...
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### damage from an Asteroid

If an Asteroid, the size of the one that killed off the dinosaurs , passed by very close to the Earth but still remained outside of Earth's atmosphere, would it cause any damage ?
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### How can you determine the initial volume of a planet's atmosphere?

Since the surface pressure of a planet is determined by the mass of the column of gasses above it one would surmise that to determine the pressure you must know the volume and mass of the atmosphere. ...
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### How did water get on Earth

I recently read that water more then likely got here by comets (carrying water) hitting the Earth. However it also it says the impact of a comet hitting the Earth is much greater then an atomic bomb. ...
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### Is there a threshold on distance/size for a tidal locking?

I know that some systems tend to tidal locking (such as earth-moon), which occurs basically because the difference in the gravitational pull on one side is significantly different from the pull on the ...
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### Why did Earth need material from comets to assemble the raw materials for life?

It's often speculated that matter from comets played a crucial role in the development of life on Earth. For example, Maps of Time says, Many of the ingredients of the early atmosphere (including ...
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### What is the direction of the movement of the solar system in relation to the galaxy's plane

I got from this answer that the axis of the solar system is tilted of about 63 degrees in relation to that of our galaxy, so I can assume that we move through space (at least locally) roughly in a ...
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### Do we still use the term “astronomical unit” nowadays?

An astronomical unit is defined as the measurement of distance between Earth and our Sun, my question is since distances between celestial objects beyond our solar system are vast and unimaginable ...
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### Can an asteroid have a molten core? [migrated]

Most natural satellites in our solar systems is expected to contain a fission furnace at it's core, some of these moons do have a striking resemblance to an asteroid. I'm wondering if we could ...
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### Find constellation over Earth coordinates on a specific date-time

I would like some help in finding the exact constellations, or some sort of visualization of the stars over an specific location an time. The idea is to find out the closest star or group of stars on ...
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### The More I Measure, The Faster I Travel [on hold]

Basically, the theme is "The More I Measure The Faster I Travel" As part of an antithesis, I am trying to destroy this statement. Can anyone help?
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### Best compact telescope for rugged use [on hold]

Is there a general variety of telescopes that are compact and rugged enough to be taken on outdoor outings, such as backpacking with exposure to cold, rain, and potential impacts?
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### Gravitational pull needed to keep a gas in atmosphere

How can you determine the gravitational force needed to keep a particular gas in the atmosphere of a planet (for example, carbon dioxide (CO2))? I came across the following formula ...
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### How much of the Milky Way is visible to the naked eye from earth?

When we see the Milky Way on a dark night are we seeing the bulk of the galaxy, or just our local arm? How much of the milky way is visible to the naked eye on a dark night?
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### average number of exoplanets in a system

I was just wondering what the normal amount of planets is in a star system, because in my mind 8 planets seems like a relatively large amount. so are we above average? can we even see all the ...
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I have, for years, been an Astronomy and physics nerd. For the first while, I was a total astronomy nerd. Then I slowly transitioned into physics and have been, for less than a year, a physics nerd. ...
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### Is there a simple, analytical formula for the lunar phase brightness curve?

Brightness of the lunar disk varies as a function of phase angle. This phenomenon is very well established, as is the increase in brightness at low phase angles. Is there a simple analytical formula ...
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### Why there is no smoke around the Sun?

Where there is fire, there is always smoke. So why there isn't any smoke near the Sun?
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### How to convert horizontal coordinates using NOVAS?

I'm using NOVAS 3.1. I know that I can convert equatorial coordinates to horizontal coordinates using the equ2hor function. Is it possible to make NOVAS do the ...
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### BIG Problem with the Planet definition

Ok, so Pluto is only ~1/13 the mass of the objects in "its orbit". This orbital region extends from 40 AU to 70 AU (semi major axes)- Now, just a minute. 30 AU is all the mass we are considering. Now, ...
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### Were the Voyager Golden Records tested for being decoded?

I was wondering if the microgroove golden records they put on the Voyager spacecraft, along with instruction on how to decode it, were first put to the test with the subjects most likely to decode ...
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### SN1604, Former and Current Name of the Constellation Serphens

Kepler wrote 'De Stella nova in pede Serpentarii' describing the supernova of 1604, now known as SN1604. My understanding is that the constellations used by Kepler and the constellations used today ...
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### What were the challenges for the ancients to observe the orbit of the Moon (instead of Mars)?

Astrophysics can be said to have been founded by Johannes Kepler around the year 1600. He based his break-through science on data of the position of Mars in the sky and disproved the ancient ideas ...
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### Lack of planets in the Oort Cloud

With the current news about the possibility of a planet in the Oort cloud, I was thinking, why is the matter in the Oort cloud distributed so? It makes sence that inside the planet region there is not ...
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### What is the Northernmost Latitude of Saturn?

My wife and I were watching a TV show last night, which takes place in Salem, Massachusetts circa 1693. One character went to a particular place in the woods at a particular time to be exactly under ...
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### Gravitational waves detector arm length and GW wavelength

What is the relation between the arm length of gravitational wave detectors and the wavelength of target gravitational waves? For example, LIGO detector has 4 km arms and detects waves with 10^2-10^4 ...
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### Total solar eclipse, supermoon, and spring equinox all happening at the same time: anything special about this?

Today (March 20, 2015) is seeing a rare combination of the spring equinox, a total solar eclipse, and a supermoon. I am wondering if there is anything special astronomically about all three of these ...
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### Mars night sky - stars visible

How would the night sky look like from Mars surface. Would there be more stars visible or less (compared to Earth) Would they appear brighter/dimmer/same.
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### Why solar eclipse paths are symmetrical?

Reading upon the eclipse of March 20, 2015, I stumbled upon this page: http://www.timeanddate.com/eclipse/list-solar.html. What caught my eye is that for each year there are two eclipses whose paths ...
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### .2015: When last did both New/Full moon in a fort-night cause an Eclipse?

Going through http://earthsky.org/…/dates-of-next-lunar-and-solar-eclipses I made the (what was for me - momentous) discovery that March 20, 2015 - New moon - is a Solar Eclipse, and that the ...
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### How to learn data analysis for radio telescope?

I have done some research about Radio Astronomy to build a radio telescope with a number of arrays. I have read one of the prerequisites of working with radio telescope is a good knowledge about ...
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### Naming of the planets of the solar system

Planets of the solar system have been named with Roman mythology gods names. I have a few questions on my mind concerning that subject for a while: Who decided to name them like this? When did the ...
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### What kind of telescope do I need to see most of the Jupiter's moons?

I have a simple Newtonian reflector telescope. Using it, I am able to see the Galilean moons of Jupiter. However, Jupiter has much more moons than that (Wikipedia says 67 have been discovered this ...
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### Sky view from Stellarium software vs. Sky view with naked eye

I'm slowly starting to interest in astronomy. Currently I'm enjoying in stargazing but unfortunately place where I live is very light polluted. I'm planing my vacation in a couple of months and one ...
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### How rare are earth-like solar eclipses?

Solar eclipses on the earth are so spectacular because the moon has roughly the same size as the sun when viewed from the earth's surface. This is an incredible coincidence, and my guess is that it is ...
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### Is stacking welder's glasses a safe way to watch at the eclipse?

You can find in many place on the Internet that welder's glass #14 is good for looking at an eclipse. Tomorrow (March, 20th 2015 at 10:45 CET) there's a solar eclipse and yesterday I could only find ...
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### Is starquake unique to neutron star?

I read from somewhere that astronomer use X-ray to observe the "shaking" not to be confused with wobbling of a distant neutron star, I think it is similar to what geologist using microphone to ...
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### Does our sun/solar system orbit around any other celestial objects? [duplicate]

Does our solar system orbit around another massive celestial object? Like a massive star or black hole for instance? From my understanding our sun rotates around the centre of our galaxy, thus our ...
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### Mass resolution

Can someone define mass resolution in terms of cosmological simulations such as the millennium simulation? Is it just the smallest mass that a dark mater particle can have and still be detected by the ...
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### Why did Venus not lose its atmosphere without magnetic field?

It is often stated that the magnetosphere not only shields the planet from cosmic radiation, but also prevents atmosphere loss. Why did then Venus not lose most of its atmosphere if it doesn't have a ...