Some stars make more nuclear fusion, or just have more energy.
'Appear' would become 'appeared' in the past tense so the sentence would simply be 'some stars appeared to be brighter than others'.
Because some are larger than others and some are closer than others.
Stars appear brighter depending on their size, temperature, and distance from Earth. Larger and hotter stars emit more light, making them appear brighter. Additionally, stars that are closer to Earth will appear brighter than those that are farther away.
Stars appear brighter if they are closer to Earth, have a higher intrinsic luminosity, or if they emit more light in the visible spectrum. Factors like size, temperature, and age can also impact how bright a star appears to us. Additionally, the presence of dust, gas, or other objects in space can affect how much of a star's light reaches us.
It is better to say that the sun appears brighter because it is closer. Some stars are actually brighter than the sun.
'Appear' would become 'appeared' in the past tense so the sentence would simply be 'some stars appeared to be brighter than others'.
Because some are larger than others and some are closer than others.
How big, how hot (color/amount of energy emitted), how far, light pollution at viewing site
No it is not. It is less bright than some, but brighter than others.
The Sun is bigger than some stars and smaller than others. It is brighter than some stars and dimmer than others. Relative to the Earth it is much closer than all other stars.
Because they are closer or actually brighter.
Stars appear brighter depending on their size, temperature, and distance from Earth. Larger and hotter stars emit more light, making them appear brighter. Additionally, stars that are closer to Earth will appear brighter than those that are farther away.
Stars appear brighter if they are closer to Earth, have a higher intrinsic luminosity, or if they emit more light in the visible spectrum. Factors like size, temperature, and age can also impact how bright a star appears to us. Additionally, the presence of dust, gas, or other objects in space can affect how much of a star's light reaches us.
because the sizes and the distances away from earth are different
It is better to say that the sun appears brighter because it is closer. Some stars are actually brighter than the sun.
"Luminous" in this context means "bright" - how much light (or how much energy in general) does the star emit. Note that stars look dim to us only because they are far away - some of them are actually several times brighter than our Sun, in absolute terms. That is, if you would see several stars, and our Sun, at a same standard distance, some stars would be dimmer, but others would be brighter, than our Sun.
Some planets seem brighter - not all of them. Planets are quite near to us, as compared to the stars.