When you observe stars through a telescope, the appearance of circles with a moving shield over them is not actually related to the stars themselves. It is likely an artifact or optical phenomenon caused by the telescope or atmospheric conditions. Here are a few possible explanations:
Telescope optics: Telescopes consist of lenses or mirrors that focus light, and sometimes these optical components can introduce certain aberrations. One common type of aberration is called spherical aberration, which can cause the stars to appear as blurry circles instead of sharp points of light. This effect is more noticeable with lower-quality telescopes or when using high magnification.
Atmospheric turbulence: The Earth's atmosphere is not completely still, and its turbulent nature can distort the incoming light. This effect is known as atmospheric turbulence or "seeing." When observing stars through a telescope, the light passes through different layers of the atmosphere, causing the image to shimmer or twinkle. This can create the illusion of a moving shield over the stars.
Misaligned or dirty optics: If the telescope's optics are not properly aligned or if they have dust or debris on them, it can affect the quality of the observed image. Misalignment or dirt on the lenses/mirrors can introduce additional aberrations, leading to distorted star images.
To improve the quality of your observations, you can try the following:
Use a higher-quality telescope: Higher-quality telescopes with better optics can minimize optical aberrations and provide clearer images of celestial objects.
Choose observing conditions wisely: Observe stars when the atmospheric conditions are favorable. Selecting nights with good "seeing" conditions, such as when the air is calm and steady, can reduce the effects of atmospheric turbulence.
Maintain and clean your telescope: Regularly clean the optics of your telescope and ensure that they are properly aligned. Follow the manufacturer's instructions or consult a professional if you are unsure about the maintenance procedures.
Remember, stars are actually distant celestial objects that emit light. Their appearance as points of light can be affected by various factors, including the telescope's optics and atmospheric conditions.