Why do some stars never leave the night sky, while others vanish for months

Everyone likes to stare at the sky at night, and when we look at the stars, it makes us feel at ease, which can help us sleep better; however, few of us take the time to consider how the twinkling sky is always changing. Some of the constellations will always be there for you at night, while others appear to disappear from view for several months and then slowly disappear or reappear yearly. The reason that some stars will remain ‘permanent’ above the horizon and others that will be ‘seasonal’ is due to the Earth's complex path through space.By understanding how our planet orbits and the tilt of the Earth, we can understand how the stars appear to change in position throughout the year and learn about which stars will remain as ‘permanent’ guardians of our horizon and which ones will only be ‘seasonal’ ones. This orbital motion creates a shifting celestial perspective, ensuring that while circumpolar stars remain constant, seasonal constellations gracefully cycle through our ever-evolving nocturnal landscape.Circumpolar stars are those that appear to be in a fixed position relative to the observer. According to NASA Space Place and the Royal Observatory Greenwich, circumpolar stars travel in a circular path around the north and south celestial poles without ever going below the horizon.Circumpolar stars remain permanently visible because of the relationship between latitude and the Earth's axis of rotation. As the Earth rotates around its axis, which is an imaginary line from the North Pole to the South Pole, stars near these celestial poles appear to move in circles about those poles. If the circular path of a star is small enough to remain above the horizon line 365 days per year, it will be visible to an observer on the Earth's surface. NASA's various scientific sites show that where you live on Earth will determine which stars are going to be circumpolar for you.The continuing and steady position of circumpolar stars in the sky as constellations has been an important part of the story of humanity for thousands of years. Like many ancient civilisations did, people who sailed the oceans used to navigate to places far across oceans without any visible features nearby by making sure they stayed within sight of these ‘permanent’ stars.Circumpolar stars appear to move in circles around the celestial poles but never drop below the horizon (for example, Orion and Scorpius). The reason these stars appear to disappear from sight is due to Earth's path around the sun each year, as determined by the Royal Observatory Greenwich and NASA.As Earth travels around the sun, we experience a different location in space each day due to the revolution of Earth around the sun. As we shift, so does a ‘window’ of what we see at night. When Earth's location occurs in orbit on one side of the sun, we view what is known as the deep-space area of stars, but like a picture we will not see in another few months when the earth has moved to the opposite side of the sun, the stars we initially viewed earlier are still out there, though they are behind the sun (from our perspective) and hence not visible because of the sun's brightness.As Earth turns around its axis relative to the stars, all stars rise approximately four minutes earlier each evening. A complete rotation takes Earth approximately 23 hours and 56 minutes, which is known as a sidereal day. The result of this small shift will add up to approximately an additional 2 hours every month.Over time, if you keep moving this way, you will eventually have the seasonal constellations appear as though they were visible during the day. They will be there, but because of the brightness of the Sun, they will look ‘disappeared’ until they are seen again later when the Earth returns to an orbit that puts them back in view.