Halley's Observations on Halley's Comet, 1682

Dev102988 1671..1682

The development of the vertebrate brain requires an exquisite balance between proliferation and differentiation of neural progenitors. Notch signaling plays a pivotal role in regulating this balance, yet the interaction between signaling and receiving cells remains poorly understood. We have found that numerous nascent neurons and/or intermediate neurogenic progenitors expressing the ligand of ...

Comet Dust from Airborne Leonid Storm Observations

For the past five years, rare Leonid meteor storms offered unique access to cometary dust by spectacular manifestations of recently ejected dust grains, which could be observed by exceptional meteor observing techniques. The final storms, those of November 19, 2002, measured the dust distribution in a comet dust trail far from the position of the comet itself. The measured spatial and particle ...

Radar observations of 8P/Tuttle: A contact-binary comet

Arecibo radar imagery of Comet 8P/Tuttle reveals a 10-km-long nucleus with a highly bifurcated shape consistent with a contact binary. A separate echo component was also detected from large (>cm-size), slow-moving grains of the type expected to contribute to the Ursid meteor stream. ! 2009 Elsevier Inc. All rights reserved.

Radar observations of Comet 2P/Encke during the 2003 apparition

The nucleus of Comet 2P/Encke was detected with the Arecibo radar during the close approach of November, 2003, making this the first comet to yield radar detections at two different apparitions. Although the measured radar cross section of 1.0 km2 was close to that obtained in 1980, the Doppler bandwidth was nearly four times larger. Most of this bandwidth difference can simply be attributed to...

EPOXI: Comet 103P/Hartley 2 observations from a worldwide campaign