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Summary

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Gravitational fields of galaxies are so strong that they can distort, or lens, the path of light from distant objects to form widely-separated multiple images of the same background source. Small astronomical objects like stars and planets can also lens bright objects behind them, but the lensing angles are so small that only the corresponding increase in magnification can detected. Astronomers are now using these tiny ``once-in-a-million'' micro lensing needles to study the massive haystack of stars, unseen dark lenses, and planets in our own Galaxy. PLANET, a worldwide collaboration headquartered in Groningen, is collecting data that will reveal whether planetary systems like our own are common in our Milky Way Galaxy.

• What are microlenses?
• How often does microlensing occur in the Milky Way?
• What can microlensing teach us about our Galaxy?
• What are microlensing anomalies and what do they teach us?
• How can anomalies teach us about extra-solar planets?
• The PLANET collaboration (Probing Lensing Anomalies NETwork)
• Toward the future: Is our Solar System unique?
• References
• Internet Resources

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This is a HTML version of a popular talk given at the NVWS Symposium on 4 October 1997 in Nijmegen, The Netherlands. A written version (in Dutch) can be found in the Dutch magazine Zenit.

Een Nederlandse versie van dit artikel ``Op Zoek naar Andere Zonnestelsels: Sterren en donkere objekten als microlenzen in de Melkweg'' is nu in de mei 1998 Zenit te vinden.

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