Across the Sun . ... Credit Copyright: G ran Strand Explanation: A long solar filament stretches across the relatively calm surface of the Sun in this telescopic snap shot from April 27. ... How long is the solar filament? ... Tracking toward the right across the solar disk a day later the long filament erupted, lifting away from the Sun's surface. ... NASA Web Site Statements, Warnings, and Disclaimers . NASA Official: Jay Norris. ... A service of: LHEA at NASA / GSFC . ...