General:

* WASP: Wide Angle Search for Planets (a planet-hunting project)

* Whirlpool Galaxy: (M51) a spiral galaxy

* White Dwarf: A small, dense star

* Wolf-Rayet Star: A massive, hot, and luminous star

Specific Objects:

* W Ursae Majoris Star: A type of binary star

* W Sextantis: A dwarf galaxy

* Whirlpool Galaxy: (M51) a spiral galaxy

Concepts:

* Wormhole: A theoretical passage through spacetime

* Winter Solstice: The shortest day of the year in the Northern Hemisphere

* Wavelength: The distance between successive crests of a wave

Instruments:

* Wide-field camera: A camera with a large field of view

Other:

* Wobbling: A slight change in the apparent position of a star due to a planet's gravity

* Waning: Describing a decrease in the illuminated portion of the Moon

Let me know if you'd like to explore any of these in more detail!