With its shrunken polar cap and its large apparent angular size, Mars is viewed here during Martian summer and while Earth nears opposition: where the Sun, Earth, and Mars all form a straight line.

THE existence of a source in the Crab Nebula with an angular diameter of less than 1 sec of arc has been revealed by observations of interplanetary scintillation at a frequency of 38 Mc/s (ref. 1).

Using the unique capabilities of telescopes specialized on cosmic gamma rays, scientists have measured the smallest apparent size of a star on the night sky to date. The measurements reveal the ...