Questions regarding the action or process of observing a single object carefully to glean information.

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42
votes
4answers
6k views

How does the Earth move in the sky as seen from the Moon?

I just want to be sure I am visualizing this correctly, because it seems odd. The Moon is tidally locked to the Earth but there are wobbles to its motion due to libration. So from a point on the ...
31
votes
5answers
5k views

Why hasn't the “9th Planet” been detected already?

In the comments to this question, there was considerable doubt placed as to the subject of if the so called "9th planet" really exists. That wasn't really the intent of the previous question, so I ask ...
13
votes
3answers
1k views

What wavelength to best detect the “9th planet”?

We know that the reflected sunlight will make detecting the 9th planet very difficult in the visible light. Is there another band that will be more likely to detect it? What is the surface temperature ...
6
votes
2answers
184 views

Are there any galaxies which fell out of sight horizon due to cosmic expansion?

If farthest galaxies run away from us with acceleration making them exceed speed of light, we should expect them to disappear from sky among time with increasing quantity. Did we observe this? Can we ...
13
votes
4answers
1k views

Why can't we observe the Oort cloud with a telescope?

The Oort cloud is a hypothetical structure based on our observation of long-period comets. There are currently proposals to design probes to confirm the existence of the Oort cloud. Now, sending a ...
2
votes
3answers
111 views

Radio telescope targeting

How do you target a radio telescope on the precise object you wish to observe? You can point it in the general direction but how do you get the information from the exact point in the sky that you are ...
8
votes
1answer
310 views

How can we tell the difference between matter and antimatter by observation in space?

I just was wondering and searching on the internet with little luck in the topic. On Antimatter Wiki they tell the observable universe is built up by matter. I read antimatter can be detected in ...
18
votes
8answers
6k views

Why can't we see distant galaxies with the naked eye?

If light keeps travelling in a straight line, why can't we see distant galaxies with the naked eye? Surely if you stared long enough, the light from them would eventually hit your eye? I apologize if ...
5
votes
1answer
592 views

Solar Noon: meridian crossing time versus time of maximum elevation

According to the first paragraph of the Noon Wikipedia page, solar noon is the moment when the Sun crosses the meridian and is at its highest elevation in the sky. The wording there suggests that ...
5
votes
4answers
304 views

How are rogue planets discovered?

Planets are usually found by observing a star and waiting for the light level to drop when a planet passes in front of it, but what about rogue planets that don't have host stars?
3
votes
1answer
46 views

Will Gaia detect inactive neutron stars?

Will the astrometric precision of the Gaia space telescope be able to detect the gravitational influence of cold old solitary neutron stars on the movements of stars? At least in a statistical sense ...
2
votes
2answers
3k views

How to calculate Longitude from Right Ascension?

Considering that a star of certain declination is crossing the local meridian at the observer's zenith at an unknown location on the earth. Here, the declination of the star is equal to the observer's ...
1
vote
2answers
138 views

Color of planets

I am developing an astronomy software and need to know the color of each planet in the Solar System, when observed with the naked eye. I cannot find that information after googling for a while. Is ...
9
votes
1answer
485 views

Why does the moon sometimes appear giant and a orange red color near the horizon?

I've read various ideas about why the moon looks larger on the horizon. The most reasonable one in my opinion is that it is due to how our brain calculates (perceives) distance, with objects high ...
6
votes
1answer
131 views

What it would look like to observe people with a different time flows?

As I learned, that the bigger gravity source you are influenced by the more slow time ticks for you, the farther away you are from a gravity source the faster times ticks. So Imagine two different ...
2
votes
1answer
81 views

Data for red-shifting

I am looking for basic data regarding red-shifting that comes with reliable measure of distance of the emitting star.
1
vote
1answer
65 views

UTC to UT1 time corrections

Astronomic observations in geodesy. It is well understood that sun and star positions may be expressed in Greenwich hour angle and declination. Or Right Ascension Declination. And may be published ...