Not All Rings Are Equal


ringsSaturn has multiple rings around the planet. While there isn’t one ring to rule them all, not all of them are equal. The D ring appears fainter than the C ring because it is comprised of less material. However, even rings as thin as the D ring can pose hazards to spacecraft. Given the high speeds at which the Cassini spacecraft travels,collisions with particles just fractions of a millimeter in size have the potential to damage key components. Nonetheless, near the end of Cassini’s mission, missionnavigators plan to thread the spacecraft’s orbit through the narrow region between the D ring and the top of the planet’s atmosphere.

Image Credit: NASA

 

The Oyster Nebula


A hazy nebulaThis is a false color image from Hubble’s Wide Field Planetary Camera 2 of NGC 1501, a complex planetary nebula located in the constellation of Camelopardalis (The Giraffe). NGC 1501 is a planetary nebula that is just under 5,000 light-years away from us. It has a central star shining brightly from within the nebula’s cloud. This bright pearl embedded in its glowing shell gives rise to the nebula’s popular nickname—the Oyster Nebula.

While NGC 1501’s central star blasted off its outer shell long ago, it still remains very hot and luminous, but it can be difficult to spot through modest telescopes. The star seems to be pulsating, varying quite significantly in brightness over a timescale of just half an hour. While variable stars are not unusual, it is unusual to find one at the heart of a planetary nebula.

Image Credit: ESA / NASA

I Zwicky 18


I_Zwicky_18I Zwicky 18 is a dwarf irregular galaxy located about 59 million light years away. Spectroscopic observations with ground-based telescopes showed that I Zwicky 18 to be almost completely made up of hydrogen and helium, the main ingredients created in the Big Bang, and galaxies with I Zwicky 18’s youthful appearance are typically found only in the early universe. Initial observations with the Hubble Space Telescope suggested an age of 500 million years, but later Hubble observations found faint, older stars in the galaxy, suggesting its star formation started at least one billion years ago and possibly as much as ten billion years ago. It’s possible that the galaxy may have formed around the same time as most other galaxies.

Image Credit: NASA / ESA

NGC 1187


NGC 1187NGC 1187 about 60 million light-years away in the constellation of Eridanus (The River). It’s been the home of two supernovae during the last thirty years, the latest one in 2007.

BTW, NGC stands for the New General Catalog of Nebulae and Clusters of Stars.

Image Credit: ESO

Happy 25th Birthday, Hubble


This animation provides a 3D perspective on Hubble‘s 25th anniversary image of the nebula Gum 29 and the star cluster Westerlund 2 at its core. It begins fly past foreground stars and approaches the rim of the nebula. After passing through the wispy darker clouds on the near side, the simulation shows the bright gas illuminated by the intense radiation of the new stars forming in the Westerlund 2 cluster. The pillars of dark, dense gas are being sculpted by light and strong stellar winds from thousands of stars. This visualization is intended to be a scientifically reasonable interpretation, but distances within the model have been significantly compressed.

Video Credit: NASA, ESA, G. Bacon, L. Frattare, Z. Levay, and F. Summers (Viz3D Team, STScI), and J. Anderson (STScI)
Acknowledgment: The Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI), the Westerlund 2 Science Team, and ESO