Image: Nature. Path of the shadow of KBO 55636 that swept across Earth's surface during the stellar occultation of 9 October 2009, observed by Sheppard and colleagues.

This week’s Nature features a paper by Scott Sheppard and colleagues in which they report on the first detection of a stellar occultation—when a planetary body hides a star as it moves across the sky—by a small object orbiting in the Kuiper Belt. The object, KBO 55636, is located more than 6 billion km from Earth and was observed by the team last October.

The use of stellar occultations have proved powerful in discovering planetary rings and for measuring accurate sizes of bodies located hundreds of millions of kilometers from Earth. Kuiper Belt objects (KBOs) are difficult to characterize because of their extreme faintness. Though over 1,000 KBOs have been discovered in the past two decades, little is known about their surface properties, density, and internal structure—knowledge that is essential for determining the size of the belt and its history. The stellar occultation observed by Sheppard and colleagues provided constraints on the size and albedo of KBO 55636 and shown that such observations are now possible. For more information, see the Nature paper and News and Views.

At the base of Oldoinyo Lengai

Carnegie Fellow Wendy Nelson recently returned from fieldwork at the Oldoinyo Lengai volcano, Tanzania, where she attempted to sample fresh carbonatite lava from the volcano’s crater floor. The trip to Oldoinyo Lengai, the only active carbonatite volcano in the world, was originally organized by the Geophysical Laboratory's Andrew Steele and colleagues from University College London and Imperial College London to collect samples of recent lavas near the volcano vents.

Nelson standing on the lower 1/3 of Oldoinyo Lengai's 2006 lava flow

Nelson’s previous work involving the East African Rift system allowed her to join the group to sample Oldoinyo Lengai and collect mantle xenoliths from surrounding volcanoes.  She will use the xenoliths to better understand the influence of the upwelling mantle plume and active continental rifting on volcanism as recorded in the lithospheric mantle. Nelson and the UK researchers hiked to the top of Oldoinyo Lengai, but unfortunately, the crater had grown such that they were unable to reach the bottom for sampling. Click here for more information on Nelson’s research.