astromax
  • Member for 8 years, 2 months
  • Last seen more than 2 years ago
  • Philadelphia, PA
7 answers
46 votes
8k views
What is in the center of the universe?
39 votes

I think your question is on topic, but @RhysW has linked a very helpful post in understanding why your question is a common misconception about the Big Bang. No Center There is no 'center' to the ...

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5 answers
28 votes
8k views
Why is the observable Universe larger than its age would suggest?
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22 votes

The easiest explanation for why the maximum distance one can see is not simply the product of the speed of light with the age of the universe is because the universe is non-static. Different things (...

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1 answers
24 votes
4k views
Milky Way Galaxy from Earth
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21 votes

The Milky Way Galaxy is a large spiral galaxy with some characteristic features worth mentioning: 1) The bulge - This refers to the collection of tightly packed stars located in the central region ...

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2 answers
41 votes
8k views
Why is our solar system "tipped" about 63° with respect to the plane of our galaxy?
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18 votes

The tilt of our solar system (or any star system) is determined by the net angular momentum of the gas cloud from which it formed. This might be a bit of a vague answer, but over time, the formation ...

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7 answers
34 votes
23k views
What's the fastest moving object in the universe?
17 votes

There is also another mediator particle which moves at the speed of light other than the photon. This is the gluon, which is the exchange particle for the strong force. The odd thing about the gluon ...

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4 answers
22 votes
34k views
Does the Sun belong to a constellation?
16 votes

No, it does not. The constellations are fixed (on time scales long enough for humans to consider as fixed, at least) patterns of stars which exist on the celestial sphere. This celestial sphere is a ...

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4 answers
22 votes
4k views
How would the night sky look from inside a globular cluster?
14 votes

Globular clusters occupy an interesting place in the spectrum of composite stellar systems. As you point out, they are highly concentrated populations of stars, and seem to lack any dark matter ...

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1 answers
24 votes
703 views
Future of CMB observations: How will our knowledge of the early universe change?
14 votes

This is a great question. I know of a couple of really big things about inflation people want to be able to nail down by using the cosmic microwave background. The first is measuring what are known ...

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2 answers
28 votes
2k views
What causes a star to become a pulsar?
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14 votes

It's generally dictated by how massive the star is. Remember what a pulsar is, it's a very rapidly rotating, highly magnetized neutron star. Neutron stars are a category of objects which have masses ...

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3 answers
30 votes
4k views
What is a parsec and how is it measured?
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13 votes

A parsec (abbreviated pc) is a unit of distance used by astronomers, cosmologists, and astrophysicists. 1 parsec is equal to $3.08567758 \times10^{16}$ meters, or $3.26163344$ light years (ly). A ...

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4 answers
16 votes
4k views
What is Gravitational Lensing?
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13 votes

Gravitational lensing is the bending of light by massive objects in between the observer (us), and a background source of light. It is a direct prediction of Einstein's theory of General Relativity, ...

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1 answers
18 votes
809 views
Are there any alternative explanations for the gravitational force we attribute to dark matter?
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12 votes

There are certainly people who study alternative (non-General Relativistic) theories of gravity. The most popular theories have so far been: Modified Newtonian Dynamics (MOND) - which essentially ...

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2 answers
23 votes
807 views
Why is the Hubble Telescope in space?
12 votes

There are a number of things which are important for a telescope. The first is the light collecting power of the telescope, which is simply a measure of how many photons the telescope can collect from ...

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2 answers
12 votes
4k views
How exactly is our universe mapped?
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12 votes

The simple answer is that light from the distant parts of the Milky Way Galaxy have already been traveling for that amount of time. Because light does not travel instantaneously through space, we are ...

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3 answers
20 votes
9k views
Could someone explain RA/dec in simple terms?
12 votes

The easiest way to think of equatorial coordinates is by extending lines of latitude/longitude (the geographic coordinate system we usually learn in school) out into space. The earth's equator becomes ...

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2 answers
16 votes
15k views
Why can we sometimes see the moon during the day?
11 votes

Well, the Moon reflects quite a bit of the Sun's radiation. In fact, this person states that: The visual geometric albedo of the full moon is 12.5%, but much less at other phases. In combination ...

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1 answers
17 votes
305 views
Loss of atmosphere on Mars
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10 votes

The loss of the Martian atmosphere can be mostly attributed to its mass. The reason why Earth still has an atmosphere made of lighter elements is because with larger mass comes larger escape velocity, ...

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3 answers
10 votes
6k views
How long until we cannot see any stars from other galaxies?
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8 votes

First of all, we can't see stars from other galaxies (with a few exceptions, Cepheid variable stars for example are regularly used to determine distances to nearby galaxies). As it currently stands, ...

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2 answers
13 votes
3k views
Is the Milky Way Visible from Nebraska?
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8 votes

Well, because the axis of the rotation of the Earth is not the same as the axis of rotation of the disk of the Milky Way (and also because we're transforming a 2-dimensional spherical map into a 2-...

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3 answers
14 votes
2k views
How can I safely observe a Solar Flare?
8 votes

Yes, there are filters which do block out the vast majority of light from the sun. I think it's actually only a very small (~1 angstrom) wavelength band of light which gets through. You can see some ...

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1 answers
12 votes
3k views
How much of an effect does the moon have on Earth's liquid mantle?
8 votes

Interesting question. I would say from an energy standpoint, it almost certainly it has no effect. Of course, the extreme case is Io, one of the Galilean moons whose heat source comes from the ...

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2 answers
8 votes
759 views
Which galaxy is receding from the Milky Way the fastest? What is known of the mechanism behind its recession?
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8 votes

This question may be a duplicate to: On what scale does the universe expand? The mechanism for the expansion of the universe is gravity, manifested through what's known as Dark Energy. Dark Energy is ...

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2 answers
10 votes
603 views
How to calculate the movement of the object passing near other object in space?
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7 votes

Since you're interested in the equations of motion, I would solve this problem by using Lagrangian mechanics. Essentially, find the kinetic and potential energies for these two bodies, A and B. ...

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10 answers
11 votes
4k views
What's the largest non-spherical astronomical object in the universe?
7 votes

The largest non-spherical objects which are virialized (meaning essentially dynamically relaxed; not in the process of forming or collapsing) are super clusters of galaxies (here is a list of nearby ...

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3 answers
14 votes
758 views
What is the ultimate fate of a cluster of galaxies?
7 votes

This depends where the cluster is. Large scale features of the universe (both observed and simulated) consist of filaments and voids. Below is a map produced by the Sloan Digital Sky Survey (SDSS) ...

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2 answers
18 votes
621 views
Moon orbits crossing each other
7 votes

Though it's probably very unlikely in a solar system as old as ours (~5 billion years), I would not put it out of the realm of possibilities. Most of the collisions of this scale and magnitude have ...

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4 answers
11 votes
3k views
Do all objects get larger in an "expanding universe"?
7 votes

No - Distances between objects get larger, but galaxies and clusters are dominated locally by gravity. The scale at which the expansion of the universe is significant is larger than the largest bound ...

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4 answers
19 votes
14k views
How was the core temperature of the Sun estimated?
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6 votes

The composition can be determined by taking spectra. Additionally, the mass can be determined through dynamics. If you combine these two, under the assumption that the star is in a state of ...

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1 answers
7 votes
437 views
SPH simulations
6 votes

I would recommend MPA Garching's Gadget code for cosmological simulations of structure formation. It's primarily gravitational, but I do believe you can include gas effects as well: GADGET computes ...

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1 answers
7 votes
203 views
How do astronomers find interesting events?
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6 votes

The answer to your question is yes. Many times discoveries in astronomy are serendipitous in nature - some of the most well-known discoveries fall into this category: the discovery of the cosmic ...

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