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Old 20th November 2014, 20:42   #61
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Default Re: The Astronomy Thread: FAQs, News & Trivia

After the great success of our country's mars orbital mission and watching interstellar, I have become interested in the dark sky. And there is an urge to capture it, through the lens ofcourse! I have read various forum and gathered the photography equipment required. The only thing I have no clue about is the location.
A cloudless night sky with absolutely no light, not even the moon should be present. There should be no or atleast minimum city light pollution possible.

Though it's related to photography, I think astronomy guys would be able to help me better. Please tell me a few good locations where I could take some good photos around delhi or udaipur or any where you would have tried.

Another question which if not answered will be fine - what are your thoughts about the science behind interstellar?

Thanks

Good luck with star gazing
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Old 21st January 2015, 15:02   #62
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Default Re: The Astronomy Thread: FAQs, News & Trivia

Guys, need help - URGENT !

I want to know on which days in Bangalore is the sun exactly above. I think this will be once between March-21 & June-21 and again sometime between June & September.
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Old 21st January 2015, 15:34   #63
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Quote:
Originally Posted by condor View Post
Guys, need help - URGENT !

I want to know on which days in Bangalore is the sun exactly above. I think this will be once between March-21 & June-21 and again sometime between June & September.
24th April is the first date.
Second date you can locate by spending some time on this page
http://suncalc.net/#/12.8546,77.6074,5/2015.04.24/12:23

Quote:
Originally Posted by 4k_jz View Post
After the great success of our country's mars orbital mission and watching interstellar, I have become interested in the dark sky. And there is an urge to capture it, through the lens ofcourse! I have read various forum and gathered the photography equipment required. The only thing I have no clue about is the location.
A cloudless night sky with absolutely no light, not even the moon should be present. There should be no or atleast minimum city light pollution possible.

Though it's related to photography, I think astronomy guys would be able to help me better. Please tell me a few good locations where I could take some good photos around delhi or udaipur or any where you would have tried.

Another question which if not answered will be fine - what are your thoughts about the science behind interstellar?

Thanks

Good luck with star gazing
you have to go to a dark sky location
http://www.lightpollutionmap.info/#z...ayers=B0TFFFTT

Rest is just simple weather game.
I clicked the Orion nebula(faint horsehead also visible) from Munsiyari
My attempt quality is not upto the mark. Will try again soon, with better polar alignment and some more Dark and flat frames to get higher contrast. Aim is to get the Barnards loop. Do not have any CLS filters though, will be tough unless the skies are really really clear
The Astronomy Thread: FAQs, News & Trivia-orion_stacked_1_lr2.jpg

That said, another simpler object is the Andromeda
With a 50mm lens 8 seconds exposure and ISO 3200 at F2.0, you can get a decent shot even without tracking.
That said, this is with tracking, again very few frames. Will try and do better
The Astronomy Thread: FAQs, News & Trivia-andromeda__lrx3.jpg

Last edited by tsk1979 : 21st January 2015 at 15:38.
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Old 21st January 2015, 16:40   #64
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Default Re: The Astronomy Thread: FAQs, News & Trivia

Hi All,

Since we are on the astronomy thread I want to ask a question to which I know the answer (I love everything science)

Q: Imagine that the sun disappears from the sky right now. It doesn't fade away, it doesn't make a noise, it doesn't give us any indication. It just disappears. It is no longer there in the sky.

So how long does it take for us, people on earth, to realize that the sun disappeared?
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Old 21st January 2015, 16:47   #65
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Originally Posted by SyncNest View Post
Hi All,

Since we are on the astronomy thread I want to ask a question to which I know the answer (I love everything science)

Q: Imagine that the sun disappears from the sky right now. It doesn't fade away, it doesn't make a noise, it doesn't give us any indication. It just disappears. It is no longer there in the sky.

So how long does it take for us, people on earth, to realize that the sun disappeared?
Here you go
The complete answer
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Old 21st January 2015, 18:40   #66
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Default Re: The Astronomy Thread: FAQs, News & Trivia

Quote:
Originally Posted by tsk1979 View Post

you have to go to a dark sky location
http://www.lightpollutionmap.info/#z...ayers=B0TFFFTT


That said, another simpler object is the Andromeda
With a 50mm lens 8 seconds exposure and ISO 3200 at F2.0, you can get a decent shot even without tracking.
That said, this is with tracking, again very few frames. Will try and do better
That link will be of great help! Thanks

The Andromeda capture is a nice one.

Are you using a crop sensor or a full frame?

Because a 50mm on crop would be like 75mm and hence smaller frame capture.

I was thinking of using a Canon 24mm f2.8 efs with Canon 600d. That would give me around 38mm focal length. Any other lens suggestion?
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Old 21st January 2015, 23:33   #67
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Default Re: The Astronomy Thread: FAQs, News & Trivia

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Originally Posted by tsk1979 View Post
24th April is the first date.
Second date you can locate by spending some time on this page
http://suncalc.net/#/12.8546,77.6074,5/2015.04.24/12:23
Thanks, TSK. I was checking another site, where the closest I seemed to get was a little off-top at 12:00 PM. This URL says solar noon is at 12:18 PM. Guess that was the difference.

But thanks for the link ..

Question:
Why is Solar noon different than 12:00 PM ?

Last edited by condor : 21st January 2015 at 23:38.
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Old 22nd January 2015, 00:00   #68
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Thanks, TSK. I was checking another site, where the closest I seemed to get was a little off-top at 12:00 PM. This URL says solar noon is at 12:18 PM. Guess that was the difference.

But thanks for the link ..

Question:
Why is Solar noon different than 12:00 PM ?
Because 12:00 is noon at the Indian Standard time longitude. Every other longitude gets noon at different time
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Old 22nd January 2015, 10:29   #69
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Default Re: The Astronomy Thread: FAQs, News & Trivia

Beagle 2, the British spacecraft lost for over 11 years, has been located intact on the surface of Mars:

http://en.wikipedia.org/wiki/Beagle_2#Discovery

Quote:
Images suggest that one of the "petals" on which the solar panels of the lander are mounted, failed to fully open, preventing deployment of its radio antenna, blocking communication.
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Old 27th January 2015, 19:06   #70
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Default Re: The Astronomy Thread: FAQs, News & Trivia

A few days ago, I had asked what date would the sun be right above, at Bangalore. Thanks to TSK who had responded to that.

Another question:
On March 21 & Sept 23, the sun's path would be aligned with the equator. So if a person is standing on the equator, is facing East / the sun, then his shadow would move from west to east with the course of the day - In a straight line. At mid-day, his shadow would be minimal - since the sun is right above.

Now, the question:
Is such a thing possible at any other latitude on the Earth ?
To keep it simple, since I am in BLR, can this happen at BLR also ?
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Old 9th May 2015, 12:48   #71
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Default Re: The Astronomy Thread: FAQs, News & Trivia

Trying TBHP as the last rescue.

Can anyone, with the help of simple examples explain me the theory of relativity, time dilation and the concept of space-time?

I have tried reading stuff over internet again and again but the concept is not getting into my thick head. I would be really obliged to you guys here if you help me understanding it.

Thanks in anticipation of help.

PS: Yes, it's the Interstellar effect. However, these questions have bothered me for long.

Last edited by saket77 : 9th May 2015 at 13:15.
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Old 11th May 2015, 12:37   #72
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Default Re: The Astronomy Thread: FAQs, News & Trivia

Quote:
Originally Posted by condor View Post
On March 21 & Sept 23, the sun's path would be aligned with the equator. So if a person is standing on the equator, is facing East / the sun, then his shadow would move from west to east with the course of the day - In a straight line. At mid-day, his shadow would be minimal - since the sun is right above.

Now, the question:
Is such a thing possible at any other latitude on the Earth ?
Of course yes.
As long as you are at a place which is between the tropic of cancer and the tropic of capicorn!
This is the whole concept behind the notion of tropics.

Quote:
Originally Posted by saket77 View Post
Can anyone, with the help of simple examples explain me the theory of relativity, time dilation and the concept of space-time?

I have tried reading stuff over internet again and again but the concept is not getting into my thick head. I would be really obliged to you guys here if you help me understanding it.
Let me try to ask you a question:
Q1: IF you a traveling at speed of X (with reference to say a distant "stationary" star), and you throw a ball directly ahead at speed of Y, what would be the speed of this ball (with reference to say a distant "stationary" star)?

A1: X+Y

Q2: What happens in case instead of throwing ball, you switched on your headlights. Does the light beam also travel at X+Y?

A2: ___
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Old 11th May 2015, 12:44   #73
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Originally Posted by alpha1 View Post
Let me try to ask you a question:
Q1: IF you a traveling at speed of X (with reference to say a distant "stationary" star), and you throw a ball directly ahead at speed of Y, what would be the speed of this ball (with reference to say a distant "stationary" star)?

A1: X+Y

Q2: What happens in case instead of throwing ball, you switched on your headlights. Does the light beam also travel at X+Y?

A2: ___
First of all thanks Alpha for the courage Courage as not for answering the question, but for trying making me understand!

Coming to your question, I think the answer is Only Y and not X+Y because speed of light is constant. I don't know the logic behind this, but this is from what I have read. I may have misread and I may be wrong though.

Thanks!
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Old 11th May 2015, 14:23   #74
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Quote:
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I think the answer is Only Y and not X+Y because speed of light is constant.
Q1: Why?

More important:
Q2: In the first example why did we assume that the ball's velocity will be X+Y?
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Old 11th May 2015, 14:43   #75
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Quote:
Originally Posted by alpha1 View Post
Q1: Why?
No idea why the speed of light does not change in this example. I am not even sure if I am right.

Quote:
Originally Posted by alpha1 View Post
More important:
Q2: In the first example why did we assume that the ball's velocity will be X+Y?
As for a stationery observer outside of the car, the ball is traveling at the speed of the car. But for someone inside the car, the ball is stationery and is not moving. So, probably when thrown outside, X+Y?
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