410 Answered Questions for the topic astronomy

Astronomy Astrophotography

06/05/19

Why do astronomers never put a scale on their photographs?
Why do astronomers never put a scale on their photographs? I have been looking at images of the Bird nebula, a collision of three galaxies, but in none of the dozen or so that I have found, nor in... more
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06/05/19

How to explain the existence of heavier elements in Population I stars and in Population II stars contain lighter one?
Recently I read Astrophysics Notes where I found a statement that young stars are classified as Population I stars and relatively older one as Population II stars. Population I stars contain... more
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06/05/19

Galaxy Spectra: Emission and Absorption Lines?
Spectra from galaxies include both absorption and emission lines. I do understand how both types of spectral lines are produced but I am not quite sure where each type is coming from when we... more
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06/05/19

Why don't the relative positions of stars and other objects in a galaxy change over the year?
Though the identifiable stars in a constellation (say Andromeda) and a galaxy (say the Andromeda galaxy) are situated light years apart, why doesn't the galaxy appear at different positions with... more
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Astronomy Cosmology

06/05/19

How is Doppler redshift of distant galaxies established?
Doppler redshift of distant galaxies gave first hint that the universe is expanding. I am curious to know how this redshift is actually measured and interpreted from observation. Suppose I observe... more
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Astronomy Biology Vision

06/05/19

How much sky do we see at any one moment?
When we look at any particular point the sky, what percentage of the celestial sphere do we see? This question arises from the notion that on average there passes one meteor per hour overhead. So... more
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Astronomy Telescopes

06/05/19

Why are telescopes on top of Mauna Kea instead of Mauna Loa?
Many large and important telescopes are located on top of Mauna Kea on Hawaii. This is a great location for many reasons: it's tall enough to be above the weather, an inversion layer at night keeps... more
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06/05/19

Why is the Hubble Space telescope able to see farthest in the universe?
What determines how far a telescope can see in the universe? How does recording data for a very long time (~10 years) help? If we could build a telescope which work at microwave region, will it be... more
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06/05/19

Did I see two Milky Ways next to each other?
I am from the northern hemisphere and as far as I remember, the Milky Way was "single lane", just one stripe. At least, this is what I recall the Milky Way to look like when seeing it from near... more
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Astronomy Moon

06/05/19

Is there any evidence for the claim that the moon was once part of the Earth?
There is a hypothesis that says a part of the Earth was split away and became the Moon.Is there any scientific evidence for this claim?
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Astronomy Planets Stars

05/18/19

How are newly discovered objects (stars, planets, galaxies...) named?
When a new astronomical object (star, planet, galaxy, comet, etc.) is discovered, what is the official procedure to name it? Who decides about the name of it? Can they be changed in time?Extra... more
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Astronomy Science

05/14/19

Define the term light year
Talking about distance
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Astronomy Solar System

05/14/19

How is the Plane of the Solar System oriented to the Sun's motion through space?
How is the [Plane of the Solar System](http://en.wikipedia.org/wiki/Ecliptic) oriented to the Sun's motion through space: parallel, perpendicular, or some other angle?
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Astronomy Education

05/14/19

What are good resources for someone looking to become an amateur astronomer?
What resources would you consider to be essential for an amateur astronomer?
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Astronomy Moon Eclipse Sun

05/14/19

Why is a new moon not the same as a solar eclipse?
Forgive the elementary nature of this question:Because a new moon occurs when the moon is positioned between the earth and sun, doesn't this also mean that somewhere on the Earth, a solar eclipse... more
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05/14/19

How many stars are in the Milky Way galaxy, and how can we determine this?
I have heard multiple estimates on the quantity of stars within our galaxy, anything from 100 to 400 billion of them. The estimates seem to be increasing for the time being. What are the main... more
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Astronomy Time Metrology

05/13/19

Why are leap seconds needed so often?
In Coordinated Universal Time (UTC), leap seconds are added to account for the slowing down of Earth's rotation. But the slowing down is said to be of the order of milliseconds in a century. Then... more
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05/13/19

What methods can astronomers use to find a black hole?
How can astronomers say, we know there are black holes at the centre of each galaxy?What methods of indirect detection are there to know where and how big a black hole is?
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05/13/19

How is it possible for astronomers to see something 13B light years away?
In a NPR News story from a few years back:> "A gamma-ray burst from about 13> billion light years away has become> the most distant object in the known> universe."I'm a layman when it... more
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05/13/19

What is the most distant object from the Earth that a spacecraft has visited to date?
What is the most distant object from the earth that a spacecraft visited has visited so far? What was the mission and when did it happen?
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Astronomy Planets Stars

05/13/19

Is it possible to see satellites with the naked eye?
Every now and then I notice some very bright "stars" in the sky. They tend to be very few (one or two, usually), and are quite much brighter than any other star out there. Often they're perfectly... more
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05/13/19

Is it possible to 3D print a mirror to create a high quality telescope?
Is it possible to 3D print a mirror with todays available materials?If so, would there be a reduction in image quality?
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05/12/19

Could evidence of a signal from an exocivilization be found in the geologic record?
We know that the current SETI efforts have not found evidence for the existence of intelligent exo-civilizations (XCIV). There also has not been any evidence found of ancient non-human... more
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05/12/19

How would we see a near-lightspeed object emitting light?
Consider an object travelling near the speed of light relative to us (let it be a spaceship or a star), which is emitting light (consider it monochromatic resulting from a two level electronic... more
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Astronomy Planets Moon Definition

05/12/19

Is the moon a planet?
Can our moon qualify as a planet? With regard or without regard to the exact definition of the planet, can the moon be considered as planet as Mercury, Venus and Earth etc. not as the satellite of... more
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