Category Archives: planetary science

ceres, dawn mission, dwarf planets, planetary science, planets

Ceres Gets a Visitor

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Dawn Mission Achieves First-ever Orbit around a Dwarf Planet

NASA’s Dawn spacecraft has become the first mission to achieve orbit around a dwarf planet. The spacecraft was approximately 38,000 miles (61,000 kilometers) from Ceres when it was captured by the dwarf planet’s gravity at about 4:39 a.m. PST (7:39 a.m. EST) Friday. These images were taken while Dawn was still inbound, on March 1, 2015.

This year is truly the Year of the Dwarf Planet! Earlier today, NASA’s Dawn spacecraft slipped into orbit around dwarf planet Ceres and settled in for a long-term study of this little world. Think about what this achievement means. First, this isn’t the first world the spacecraft has orbited. It also studied the asteroid Vesta for about a year. That makes it the only spacecraft (so far) to orbit two extraterrestrial targets.

Second, it will be the first of two missions this year to give us up-close looks at dwarf planets. The long-awaited New Horizons mission to Pluto and beyond will finally show us some high-resolution details of Pluto, the infamous dwarf planet that is at the heart of so much controversy about what the word “planet” means. I hope for all our sakes that the science we get from these two missions FAR overshadows the controversy. These are worlds. They ARE planets. The term “dwarf” in their  names is not an insult — it’s a descriptor loaded with a LOT of meaning to planetary scientists, who should know what planets are (despite the best efforts of the IAU to dictate to them otherwise). Just as there are types of stars (dwarfs, giants, etc.) and types of galaxies (dwarfs, lenticulars, spirals, etc.), there are types of planets. The cosmos is big enough to contain all the types we want. We just need to recognize that and move on.

Already, Ceres is tantalizing us with a bright spot, a cratered surface, and various other characteristics. This tells ME that this little world, as well as Pluto, has some secrets to share, and that those secrets will enlarge our understanding of the solar system. Knowing our own neighborhood is an important first step toward understanding worlds far beyond our own star, and it helps us “get” where we are in the cosmos. So, stay tuned. Ceres has a lot to show us, and in a few months, Pluto will take its place on center planetary stage and continue the show of a lifetime.

 

 

 

astronomy, Orion, planet-forming scenarios, planetary science, radio astronomy, star formation

Orion’s Pebbled Pathway to Stars and Planets

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Radio Astronomy Reveals a Long and Winding Road in Space

Radio/optical composite of the Orion Molecular Cloud Complex showing the OMC-2/3 star-forming filament. GBT data is shown in orange. Uncommonly large dust grains there may kick-start planet formation. Credit: S. Schnee, et al.; B. Saxton, B. Kent (NRAO/AUI/NSF); We acknowledge the use of NASA’s SkyView Facility located at NASA Goddard Space Flight Center.

Wow!  Check out this latest image of the Orion Nebula!

Just when you think astronomy can’t get any cooler, something like this comes out: radio astronomers using the Green Bank Telescope (a radio telescope in West Virginia) have found filaments of star-forming gas near the Orion Nebula. Embedded in those filaments are what they think could be large grains of rocky material, the building blocks of planets.

If this discovery is held up through further observations, it would be the first time large particles — perhaps the size of a Lego-type building block — have been detected in such a dense super-nurturing star- and planet-forming nursery. Prior to this, regions of star birth were understood to be thick with dust-sized grains.  The existence of larger grains could change the dynamic of planet formation in this and other regions where larger particles exist.

Scott Schnee, an astronomer at the National Radio Astronomy Observatory (NRAO) and lead on the team doing the work, pointed out that the availability of large-enough (pebble or Lego-sized) planetary building blocks would encourage the formation of planets around newborn stars in the region. “If you want to build a house, it’s best to start with bricks rather than gravel,” he said, implying that it would lead to faster building rates than normal.

Planet formation, similar to building a house, needs material to get started. Most planet nurseries start out with grains of material perhaps no larger than dust specks or maybe sand bits. Over time, those materials stick together to form larger and larger planetesimals, which collide to form planets. If you can start with bigger pieces, that might shorten the planet formation time.

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