Venus and Bright Planets Through a Large-Scale Camera Obscura: Optical and Mechanical Issues of Conducting the Observations

Abstract

The article describes observations of the crescent of Venus and other bright planets using a large camera obscura. The goal of the article is to demonstrate that these observations can be successfully performed. Achieving positive results depends on solving several key problems. The most significant of these is the difficulty of perceiving the extremely faint light of a planet on the camera obscura screen. This issue is resolved through the use of special directional screens. Two main types (translucent and reflective) are described in the article. The construction of a so-called ``artificial Venus'', designed to test directional screens and determine the average sensitivity of human vision, is also presented. \\ Other serious challenges include aiming the camera obscura at the celestial object and compensating for Earth's rotation. One of the methods discussed involves the use of a flat intermediate mirror and a special mount for its guidance.\\ The objective of the paper is fulfilled through the presentation of both visual and photographic observation results. In addition to Venus's crescent, observations of the Saturn's rings are also presented. The proposed design of the camera obscura, which incorporates a specialized projection system, enables the separation of its two functions: directing light from objects and focusing its energy. The elements performing these tasks are fully scalable. This can be used in the construction of modern telescopes. The article also comments on the possibility of observing the phases of Venus in the distant past and the important consequences resulting from this.