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12
votes
1answer
221 views

How can only 1 magnetic pole of the Sun change at a time?

I read some news stories about the current Solar maximum and the flipping of the magnetic poles. They say that one of the magnetic poles has switched polarity and the other will switch in about a ...
6
votes
1answer
229 views

Can I see comet ISON from Saudi Arabia?

I live in western Saudi Arabia, I am trying to see the comet ISON, reading here and there tells that I can see it by naked eye somewhere next to the constellation leo, I used an app to tells me where ...
11
votes
1answer
696 views

Inflation cosmology: slow-roll inflation versus tunneling between two vacua

In slow-roll inflation models, the early inflation of the universe is driven by the flat non-zero part of the inflaton potential, and it ends as the ball rolls down the cliff and the potential energy ...
6
votes
1answer
412 views

How can the equation of state for cosmic strings and domain walls be derived?

In this article which nicely explains why it is really the quantity $\rho + 3p$ which is relevant to determine if the expansion of the universe is accelerating or decelerating by making use of the for ...
5
votes
1answer
96 views

Why is there billowing dust in nebulae?

Why do some nebulae look like the billowing clouds? Wouldn't that require something like a viscosity in empty space?
4
votes
1answer
759 views

How does a Bahtinov mask work?

For focusing the image of a telescope, one can use a Bahtinov mask. How does this mask work, and how did Mr Bahtinov get the idea to cut such a peculiar shape? Is it possible for me to design my own ...
10
votes
1answer
205 views

Crab Nebula Time Period

I've learned that the time period for a rotating neutron star, i.e., a pulsar is very accurate and can be used as an interstellar clock. But according to Walter Lewin's 8.01 Lec 19 on classical ...
10
votes
1answer
217 views

How are the newly discovered Janus/Epimetheus rings different from the other rings of Saturn?

What are the newly discovered ring systems of Saturn, and the circumstances relating to the discovery? Is there something that makes them different from the old well-known rings, like their formation? ...
4
votes
1answer
612 views

Open data for satellites positions

Is there a site / service where I can get the data for the positions of satellites (I mean artificial satellite, ISS, etc.)? I know that some sites provide a visualization of these positions, but I'm ...
1
vote
1answer
763 views

Solar maximum and minimum

What are solar maximum and solar minimum? Is there a relation between sun spots and solar maximum and minimum? Thank you!
5
votes
1answer
216 views

How can we be sure that we have identified very distant stars correctly?

From reading this question on calculating distance to stars and from a bit of background reading on the standard candle theory I still don't see how we can confirm that a star we see at one distance ...
18
votes
1answer
5k views

What does it mean for a star to go nova or supernova? Can I safely observe these?

What does it mean for a star when people say it goes 'nova' or super nova, what are the differences? More importantly, can I safely observe these with an amateur telescope? I imagine they would be ...
13
votes
3answers
7k views

How can I calculate moon phase and height?

How could I know what phase the moon is in when it's high in the sky during sunrise? How could I tell in general what its height in the sky will be at any given time?
9
votes
1answer
94 views

Do we live in a galactic bubble?

I have heard a certain statement, which can be summarized succinctly into "we live in a local bubble", implying that solar system is located in an intestrellar dust underdensity region. This region ...
8
votes
1answer
275 views

How can I measure the mass of eclipsing binary stars?

Is there any method to measure the mass of eclipsing binaries without using Doppler shift effect?
4
votes
1answer
371 views

Colossus telescope, trying to outsmart aliens?

I was listening to Jeff Kuhn's talk on SETI's Colossus telescope project. Background: He explains his theory that a civilization living somewhere the galaxy would want to hide, and thus would ...
5
votes
1answer
188 views

Planned telescope to detect alien waste-heat

I remember watching a talk by someone who designed a telescope to view a single star at a time. The purpose of the telescope was to detect waste-heat which would presumably be emitted by any ...
11
votes
1answer
5k views

What happens to a star after it has become a red giant?

When our sun reaches the end of its lifetime , it will turn into a red giant. How long will it be a red giant, and what happens after a star has been a red giant? Does it turn into a planet after a ...
7
votes
1answer
263 views

What are the next planned space telescopes?

We've had hubble for two decades. Its become the most famous space telescope, and lately Kepler seems to be running for the second place. Are there any more powerful, better telescopes planned for ...
6
votes
1answer
5k views

Most important feature of a telescope

I was taking an astronomy test, the following question came up: The most important function of the astronomical telescope is: Resolving power Light gathering power magnifying power ...
13
votes
3answers
2k views

How can I safely observe a Solar Flare?

Solar Flares obviously release extreme amounts of energy and extend thousands of miles out into space. Because they are so big I would like to be able to observe some of these events through a ...
8
votes
3answers
456 views

Is there a natural process by which hydrogen is generated from heavier elements in the cosmos?

we know that stars fuse hydrogen into helium starting at 3 MK; 13 MK in the Sun's core; carbon fusion starts at above 500 million K, and silicon fusion starts at over 2700 million K for comparison; ...
6
votes
4answers
593 views

Can it be inferred that our cosmological horizon has increased over time?

If I am right, we can see only those stars that lie within our cosmological horizon, and there may or may not be any stars beyond that. Given last 150 years of using telescopes, and since then our ...
6
votes
1answer
2k views

What is a 'hybrid' eclipse?

As mentioned on the NASA eclipse website the eclipse on the 3rd of November 2013 will be a "Hybrid" eclipse. I have looked at the diagram on that page but can't see what is different about the ...
12
votes
1answer
330 views

Changes to Earth's orbit

Any time a spacecraft comes in close proximity to a planet and if the spacecraft has the right angle then it is able to use the planet's velocity to move itself further into space. According to ...
12
votes
1answer
216 views

Do planetary rings have geometric bounds?

Are there any bounds on where a planetary ring can form and maintain orbit relative to the planet? Do they have to be in a circular equatorial orbit? Is there a min or max altitude, say with respect ...
27
votes
2answers
3k views

What is a parsec and how is it measured?

Astronomical units of measurement are mostly pretty straight-forward: Astronomical Units refer to the mean Earth-Sun distance (~150 million km or 93 million miles) Light years are the distance light ...
14
votes
2answers
744 views

What is radiation pressure and how does it prevent a star from forming?

This is a follow up to: Is there a theoretical maximum size limit for a star? The answer there talks about the radiation pressure preventing a star from forming. What reaction is causing this ...
20
votes
1answer
523 views

Future of CMB observations: How will our knowledge of the early universe change?

The Planck satellite has been presented and awaited for a long time as the ultimate experiments for measuring temperature fluctuations in the cosmic microwave background (CMB) over the full sky. One ...
21
votes
2answers
703 views

Why is the Hubble Telescope in space?

Why is the Hubble Telescope in space? Do we get enhanced clarity and range by placing it in space? What can it achieve from space that it could not achieve from Earth?
5
votes
1answer
66 views

How can I observe the Orionid Meteor Shower?

I would like to see the orionids sometime this week (October 20-26, 2013). What is the best way for me to observe them by naked eye? Also, would I be benefitted by trying to look at them with a ...
3
votes
0answers
52 views

How is the distance from Earth to distant celestial bodies calculated? [duplicate]

It's difficult for most people to grasp how distances between the Earth and distant celestial bodies are calculated. For example, when someone tells me that a given star is 100 light years away, how ...
5
votes
1answer
116 views

How much did we know about asteroids at the beginning of the 20th century?

When was the nature and size of asteroids discovered? I was under the impression that it was not until the 1980s or 1990s with deeper space probes and Hubble imagery that we learned the nature of ...
6
votes
1answer
363 views

Does gravitational lensing cause a black-hole to be the main 'source' of light in a given area?

Light gets bent around high-gravity sources, such as a black-hole. A source of light, say A, is directly observed in its 'true' position and some of its light is bent around the black-hole, X, which ...
16
votes
2answers
885 views

What are practical considerations for backyard radio-astronomy detection of black holes?

Evidently, direct observation of a black hole for an amateur astronomer, such as described for what professionals do in the question "How are black holes found?" would be nigh on impossible, so the ...
6
votes
1answer
1k views

Periodic error correction in automatic telescopes

I am starting a study on automatic telescopes and the correction of their periodic error. I found two ways of correcting it : with a CCD camera and manually by recording the error. I was wondering if ...
16
votes
1answer
586 views

On what scale does the universe expand?

According to the theory (or my understanding of it), the universe is not only expanding, but speeding up. If the galaxies are moving apart, are the solar systems within them also moving apart from ...
15
votes
1answer
123 views

Loss of atmosphere on Mars

If the atmosphere on Mars was once much thicker, how was it likely lost? Was it due to interaction with the solar wind, the small size of the planet, both, or something else, and approximately how ...
-2
votes
1answer
2k views

Is it possible the Nebular Hypothesis and Planetesimal Theory are not correct? [closed]

For almost 3 centuries now the Nebular Hypothesis and Planetesimal Theory have become the preeminent explanations for how the Solar System and Planets evolved. Yet there is still no explanation for ...
10
votes
1answer
728 views

Timescale of ignition of a protostar?

What is the timescale of start of nuclear fusion as T Tauri type star transforms into a Main Sequence star? Wikipedia article on T Tauri type stars mentions: Their central temperatures are too low ...
10
votes
1answer
298 views

What might cause a planet to have a significant tilt in their orbit?

Most of the planets in our solar system all orbit along the same plane, supposedly because of the almost flat dust clouds that formed the planets. But some planets, such as the one featured below, ...
10
votes
1answer
588 views

Why does Pluto's Orbit underlap Neptune's Orbit

Why does Pluto's Orbit underlap inside of Neptunes Orbit. Clearly Neptunes Orbit is not overlapping on Pluto's. Yet, they fail to maintain the symmetric banding appearance all the other Planets ...
5
votes
2answers
269 views

What is the furthest object in the observable universe?

My question is about furthest object in the observable universe except Сosmic microwave background.
0
votes
3answers
153 views

Why does Astronomy still use the Anno Domini system for Time Synchronization

Since Time is such a valuable variable in the calculation of Astronomic movement why does the Astronomy Community still rely on the the 6th Century Anno Domini system developed by Dionysius Exiguus to ...
7
votes
1answer
50 views

Are we still in the Solar Maximus stage? Will this winter 2013/14 be a good aurora-viewing season?

I remember reading in 2011 that 2013/2014 would be the peak of the current solar maximus, but I want to confirm whether that is still ongoing. Will the upcoming winter season be a good time to see ...
13
votes
2answers
169 views

Relativistic effects in stellar dynamical systems

I am curious, if anybody knows of any stellar dynamical systems/environments, where relativistic effects could play a dynamical role on the motion of these stellar systems? As a subquestion - are ...
10
votes
1answer
168 views

Dealing with damp and dew whilst stargazing at night or in the early morning

Sometimes when using my telescope late at night or early in the morning, especially in the more humid of seasons, I notice i sometimes get dew buildup on the lenses. How can I minimize damp buildup ...
10
votes
1answer
444 views

How can I clean my lenses without causing scratching or damages to the lens surface?

Sometimes you can be trying to observe very faint or very small objects in the sky and it wouldn't pay to have these obscured or marred by a scratch or dust on the lenses. I keep to good practices ...
10
votes
1answer
2k views

What effects do other planets have on the solar system?

For instance, Jupiter is the biggest planet in our solar system. Due to it's gravitational mass it can deflect meteorites and protect Earth from the Oort cloud. While these are positives, the ...
7
votes
2answers
1k views

Why are some planets so close to their star?

"Kepler-10b orbits its parent star once every 0.84 days, which means it is more than 20 times closer to its star than Mercury is to our sun" space.com Are there any accepted theories that ...

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