Detecting planets around a star without using telescopes or spacecraft is extremely challenging, if not impossible, given the limitations of human vision and the vast distances involved. Here are a few reasons why this is the case:
Distance: The nearest star to Earth, apart from the Sun, is Proxima Centauri, which is approximately 4.24 light-years away. Even if there were planets around Proxima Centauri, they would appear as faint points of light from Earth without the aid of telescopes.
Size and brightness: Planets are much smaller and less luminous than their parent stars. They do not emit their own light but instead reflect a portion of the star's light. This makes them significantly fainter and harder to detect compared to the star itself. Detecting such faint objects without telescopic magnification is beyond the capabilities of human eyes.
Angular separation: Planets are typically located very close to their host stars when viewed from Earth. The angular separation between the star and the planet is often extremely small, making it difficult to distinguish the two as separate objects without the resolution provided by telescopes.
Atmospheric effects: Earth's atmosphere can introduce distortions and turbulence that affect the clarity of celestial observations. Telescopes and space-based observatories are designed to mitigate these effects and provide clear and accurate images.
While there have been instances of amateur astronomers detecting exoplanets indirectly through observations of a star's brightness variations (known as transit photometry) or the wobble of a star caused by a planet's gravitational pull (known as radial velocity method), these techniques still rely on telescopes or specialized equipment to gather and analyze data.
In summary, detecting planets around stars from Earth without the use of telescopes or spacecraft is currently beyond our technological capabilities. Telescopes and spacecraft provide the necessary tools and instruments to observe and study celestial objects in detail, allowing us to explore and understand the universe more comprehensively.