Gum 41


Gum 41In the middle of this little-known nebula called Gum 41, brilliant hot young stars are giving off energetic radiation causing the surrounding hydrogen to glow a characteristic red. The nebula is located 7300 light-years from Earth. Australian astronomer Colin Gum discovered it on photographs taken at the Mount Stromlo Observatory near Canberra, and included it in his catalogue of 84 emission nebulae, published in 1955. Gum 41 is actually one small part of a bigger structure called the Lambda Centauri Nebula, also known by the more exotic name of the Running Chicken Nebula.

Image Credit: ESO

Earthshine


This video takes us around the Moon and shows how it is illuminated not only by the brilliant light of the Sun but also by light reflected from the Earth. The trip starts on the side facing away from Earth where part of the surface is brightly illuminated by the Sun but the rest is totally dark. Moving around the Moon, the Earth rises, and its reflected bluish light illuminates the Moon’s surface. This dull glow is the earthshine. (You can clearly see it from Earth when the Moon appears as a crescent in the evening or morning sky.) When the Sun emerges from behind the Moon, the brilliant crescent is seen, but the earthshine is still faintly visible.

Video Credit: ESO

A Comet’s Tail


This animation features comet C/2016 R2 (PANSTARRS). As its name suggests, the comet was discovered in 2016 by the Pan-STARRS telescopes in Hawaii. The time-lapse movie was assembled from observations taken on 18 January, 2018, when the comet was 2.85 AU from the Sun (2.85 times the Earth-Sun distance) and traveling inwards.

Comets are clumps of dust, ice, gas, and rock. When they pass close to the Sun, some of their ice warms up, turns to gas, and escapes. This process forms fuzzy envelopes around the comets’ nucleus called comas and distinctive tails.

C/2016 R2 (PANSTARRS) is interesting because of the compounds and molecules detected in its coma: carbon monoxide and nitrogen ions. These cohemicals give the comet distinctive blue emission lines, and it has been nicknamed “the blue comet”. This comet orbits the Sun once every 20 000 years. Its most recent approach was last May, so we won’t see it again for a while.

Video Credit: ESA