1) Because they HAVE different characteristics,2) Because they are at different distances,
3) Stars may also look different because of dust and gas, between us and the stars, that absorbs part of the starlight.
Because human beings are curious to know more about all things that they come across.
They were there, above their head most nights - they could not help but observe them.
You use a telescope to observe stars, and sometimes also use a star map.
You observe its motion, with respect to the background stars.
atoms
the light radiated from the stars
To observe the stars, you would use a telescope.
Stars vary in characteristics like brightness for example. Stars will also tend to differ in size and color when they are found.
At the Age of Exploration they used telescope to observe stars.
Beacuse they are dimmer, but they're also bigger than the main sequence stars.
by observing different stars in different stages of their formation
It is its property.
They were there, above their head most nights - they could not help but observe them.
telescope
determine which stars are gravitationally bound to each other
When you can observe something's characteristics, they are called physical traits. These are the things you can see, hear, smell.
Three characteristics to classify stars are their luminosity, size, and color or surface temperature.
The test flight is when you observe the flight characteristics of an aircraft.