Epicycles of Mercury and Venus, 1823
Epicycles of Mercury and Venus, 19th-century diagram. This geocentric (Earth-centred) model shows the orbits of Mercury and Venus as a series of epicycles (loops). Mercury and the Sun are at lower left. Venus is at upper right. The heliocentric system of Copernicus and Kepler replaced these epicycles with elliptical orbits around the Sun. At lower left is an astronomical quadrant. At lower right are the proportional magnitudes of 12 solar system bodies (see C017/8059) and of the Sun as seen from those bodies. The Georgium Sidus is Uranus. This page is from Universal Technological Dictionary (1823) by British author George Crabb (1778-1851)
© MIDDLE TEMPLE LIBRARY/SCIENCE PHOTO LIBRARY
Artwork of ancient Mars with water on its surface
Ancient Mars. Computer artwork of Mars at least 3 billion years ago. The surface environment of ancient Mars was different to that of today, and may have allowed life forms to develop. Ancient Mars was warm, with seas and lakes covering much of its surface; it also had a thick atmosphere (blue). Today, water is present on Mars only as ice on the surface in the polar regions, underground or as trace amounts of vapour or ice crystals in the atmosphere. The atmospheric pressure of modern Mars is only 0.6% that of Earth's, and the average surface temperature is - 33 degrees Celsius. This means that it is extremely unlikely that life still exists on Mars
© JULIAN BAUM/SCIENCE PHOTO LIBRARY
Panoramic view of Mars
February 27 to March 2, 2005 - This is the Spirit panoramic camera's Lookout panorama, acquired on the rover's 410th to 413th martian days, or sols (February 27 to March 2, 2005). The view is from a position known informally as Larry's Lookout along the drive up Husband Hill. The summit of Husband Hill is the far peak near the center of this panorama and is about 200 meters (656 feet) away from the rover and about 45 meters (148 feet) higher in elevation. The bright rocky outcrop near the center of the panorama is part of the Cumberland Ridge, and beyond that and to the left is the Tennessee Valley.
The panorama spans 360 degrees and consists of images obtained in 108 individual pointings and five filters at each pointing. This mosaic is an approximately true-color rendering generated using the images acquired through panoramic camera's 750-nanometer, 530-nanometer, and 480-nanometer filters. The lighting varied considerably during the four sols that it took to acquire this image (partly because of imaging at different times of sol, but also partly because of small sol-to-sol variations in the dustiness of the atmosphere), resulting in some obvious image seams or rock shadow variations within the mosaic. These seams have been smoothed out from the sky parts of the mosaic in order to simulate better the vista that a person would have if they were viewing it all at the same time on Mars. However, it is often not possible or practical to smooth out such seams for regions of rock, soil, rover tracks, or solar panels. Such is the nature of acquiring and assembling large Pancam panoramas from the rovers.
Spirit's tracks leading back from the West Spur region can be seen on the right side of the panorama. The region just beyond the area where the tracks made their last zig-zag is the area known as Paso Robles, where Spirit discovered rock and soil deposits with very high sulfur abundances. After acquiring this mosaic, Spirit drove around the Cumberland Ridge rocks seen here and is now driving up the flank of Husband Hill, heading toward the summit
© Stocktrek Images