Cheap vacation package for Comets that move into the zone between Earth and the Sun or move behind Earth or the Sun are boosted in their brightness. This is because the sunlight is scattered forward and backward toward Earth by the comet’s dust. The closer the comet gets to the Earth-Sun axis, the greater the brightness boost is. Image credit Sirscha Nicholl. Where lines extending to the comet from the Sun and from Earth converge at an angle = phase angle of degrees or more, this effect is notable. At degrees the comet is magnitudes brighter than at degrees. At degrees, the brightness boost is magnitudes a hundredfold boost greater than at degrees. Cheap vacation package 2016.