How can you measure angular distance in the sky?
The apparent distance between two points on the dome of the sky is the angular distance, which is the angle between the two objects, measured with the vertex at the center of the sphere (which roughly corresponds to our location). This angle is measured in degrees of arc; fractional values can be specified in arcminutes and arcseconds.
Angular size corresponds to the length or diameter of an object as projected onto the sky . It is measured in the same way as Angular distance.
The apparent distance between two points on the dome of the sky is the angular distance, which is the angle between the two objects, measured with the vertex at the center of the sphere (which roughly corresponds to our location). This angle is measured in degrees of arc; fractional values can be specified in arcminutes and arcseconds.
Angular size corresponds to the length or diameter of an object as projected onto the sky . It is measured in the same way as Angular distance.
Using your hands, you can approximately measure the angular distance in the sky
Averted Vision
Averted Vision allows us to see twice the amount of sky we could see earlier. The human eye contains two sets of light-sensitive cells: the cones which see color and the rods which see black and white. The cones are very insensitive at low light levels. (This is why you don't see color in faint objects through a telescope, but bright objects like planets still show color.) The rods take over at night because they have greater dim-light sensitivity. But the cones are located in the center of the eye, and the rods are mostly located around the periphery. This means looking directly at a celestial object uses the insensitive cones, but looking off to the side of the object puts the light from the object right onto the rods.
Averted Vision allows us to see twice the amount of sky we could see earlier. The human eye contains two sets of light-sensitive cells: the cones which see color and the rods which see black and white. The cones are very insensitive at low light levels. (This is why you don't see color in faint objects through a telescope, but bright objects like planets still show color.) The rods take over at night because they have greater dim-light sensitivity. But the cones are located in the center of the eye, and the rods are mostly located around the periphery. This means looking directly at a celestial object uses the insensitive cones, but looking off to the side of the object puts the light from the object right onto the rods.
Averted Image
Can you see a satellite from Earth?
Surprisingly there are a large portion of man made satellites that can be seen with the naked eye. If we go to areas where there are clear skies, we can spot almost hundreds of satellites in a single night.
How to identify a Satellite?
To identify a satellite, you are looking for a star that looks like it is slowly moving across the night sky.
What is an Iridium Flare?
An Iridium flare looks like a star that moves slowly and quickly brightens, then slowly fades away. If it looks elongated, leaves a visible trail, fades away in less than a second from becoming visible, or lasts more than a minute, it is most likely either a meteor, a fireball, a satellite, or the ISS (International Space Station, which can also be found by similar methods).
Surprisingly there are a large portion of man made satellites that can be seen with the naked eye. If we go to areas where there are clear skies, we can spot almost hundreds of satellites in a single night.
How to identify a Satellite?
To identify a satellite, you are looking for a star that looks like it is slowly moving across the night sky.
What is an Iridium Flare?
An Iridium flare looks like a star that moves slowly and quickly brightens, then slowly fades away. If it looks elongated, leaves a visible trail, fades away in less than a second from becoming visible, or lasts more than a minute, it is most likely either a meteor, a fireball, a satellite, or the ISS (International Space Station, which can also be found by similar methods).
Iridium Flare (the white streak near the top)
References :
https://dept.astro.lsa.umich.edu/ugactivities/Labs/coords/
https://dept.astro.lsa.umich.edu/ugactivities/Labs/coords/