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Ask an Astrophysicist

This is the "Ask an Astrophysicist" service of the Imagine the Universe! web site. We specialize in cosmic-ray, gamma-ray, and X-ray astrophysics, and other satellite based astronomical observations. Our research subjects are often exotic, like black holes, quasars and dark matter.

If you would like to ask a question or see the updated
archive of questions, please visit us online at

Which topic area are you interested in?
(Please select one)

* Astronomy as a Profession * Neutron Stars/Pulsars
* Binary Star Systems Red * Night Sky (stars, planets & more)
* Black Holes * Physics of Stars
* Cosmic Rays * Quasars & Active Galaxies
* Cosmology * Relativity
* Dark Matter and Dark Energy Red * Satellites & Space Technology
Red * Earth and Moon (also calendars) Red * Solar System
* Exoplanets Red * Space Travel & Exploration
* Gamma-ray Bursts * Supernovae and Their Remnants
* Milky Way and other Galaxies * X-ray/Gamma-ray Astronomy

Red * General Astronomy & Astrophysics

On this DVD, topics that link with * and Red * are equivalent; in the online version, only links with * allow you to submit new questions.

Not sure where your question fits in? If so, If your question does not fall onto one of the above areas, it means we are not the appropriate resource for your question.
  • Check out the "Who are we" page, which explains what we study, what questions we'd most like to answer, and how we fit in with the rest of NASA.
  • Try a list ofastronomy "Ask an Expert" services (
  • Also check the AskA+ locator ( of the Virtual Reference Desk, to find "Ask an expert" services on a wider range of subject areas.
  • Try a general web search --- a lot of the things are on the web, if only you knew where to look. Here is an explanation of how to do a web search.

Imagine the Universe is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

The Imagine Team
Acting Project Leader: Dr. Barbara Mattson
All material on this site has been created and updated between 1997-2012.

DVD Table of Contents
Educator's Index