Astronomers released Hubble images of a “light echo” around a star called V838 Monocerotis, which in January 2002 had suddenly swelled in brightness, giving off 600,000 times more light than our Sun does. Hubble’s images showed light from this outburst illuminating clouds of dust around the star as the light traveled outward. A light echo is a physical phenomenon caused by light reflected off surfaces distant from the source, and arriving at the observer with a delay relative to this distance. It is shown above.
Results from Hubble observations of ‘Oumuamua, the first known interstellar object to pass through our solar system, were announced. Hubble, along with other space and ground-based telescopes, measured the object’s trajectory and found that it gained an unexpected boost of speed. A possible explanation is that ‘Oumuamua expelled gaseous material like a comet, which influenced its path. Oumuamua is displayed above.
NASA’s Deep Impact spacecraft released a 820-pound projectile targeted at the comet 9P/Tempel 1. Hubble observations of the impact, released later that day, showed visible-light images of the comet before and after impact. The impact excavated debris from the interior of the nucleus, forming an impact crater. The gif above shows the impact.
Hubble observed the bright core of comet 17P/Holmes, which mysteriously brightened by nearly a millionfold over a 24-hour period in late October. Hubble’s observations uncovered details as small as 33 miles (54 kilometers) across, revealed spurs of dust emanating from the comet’s nucleus, and showed the cloud of dust encircling the comet (called the coma) disperse and fade over several days. The coma got fainter because it expanded. The comet is shown above.