https://www.skyatnightmagazine.com/space-science/why-do-stars-twinkle

this articke answer tthese question

The stars twinkle in the night sky because of the effects of our atmosphere. When starlight enters our atmosphere it is affected by winds in the atmosphere and by areas with different temperatures and densities. This causes the light from the star to twinkle when seen from the ground. If Earth stayed still instead of orbiting the Sun, we would always see the same constellations. The nighttime side of Earth would always be facing the same part of space. These stars and their patterns shift because of the Earth's movement as it orbits around the sun. If you measured the shifting of the night sky, you may notice it shifts one degree per day, with 360 degrees in a circle and 365 days in a year. The constellations you can see at night depend on the time of year. Earth orbits around the Sun once each year. Our view into space through the night sky changes as we orbit. So, the night sky looks slightly different each night because Earth is in a different spot in its orbit. Sadly, no observer on Earth can see all 88 constellations at once. Which star patterns one can spot at any given night depends on the time, season, the stargazer's latitude and, obviously, the observational conditions. The stars are not fixed, but are constantly moving. If you factor out the daily arcing motion of the stars across the sky due to the earth's rotation, you end up with a pattern of stars that seems to never change. There are lots of factors of this but; the main is that the earth is spherical. if you are at the northern hemisphere, you can only see northern constellation and vice versa for the south. As the Earth orbits the Sun, its nighttime side points to different constellations at different points along its orbit. What does the constellation Cygnus consist of? No, you cannot. What stars you can see from any part of the world depends on your latitude (how far north or south of the equator you are) As, where I live, at ~45N latitude, I can never see Alpha Centauri. If I were to take a trip to Hawaii, I would. Because stars are so far away, it takes years for their light to reach us. Therefore, when you look at a star, you are actually seeing what it looked like years ago. It is entirely possible that some of the stars you see tonight do not actually exist anymore. Without any orbit, Earth would likely go crashing directly into the sun. That's because our planet's path around that big, bright star in the sky is what keeps Earth from being pulled in directly by the sun's gravity. Picture yourself throwing a tennis ball off a roof. The celestial sphere would no longer rotate around the Earth. The location of the North Celestial Pole in the sky would no longer depend on the observer's latitude. We would no longer have day and night. The Celestial Equator would no longer "line up" with Earth's equator. Conversely, a shift in the orbit moving Earth farther from the sun would cool and potentially freeze the planet. Oceans would be covered in ice, causing them to release less carbon dioxide and vapor.