- Rosario Strait (Wikipedia)
Rosario Strait is a strait in northern Washington state, separating San Juan County and Skagit and Whatcom Counties. It extends from the Strait of Juan de Fuca about 23 kilometres (14 mi) north to the Strait of Georgia. The USGS defines its southern boundary as a line extending from Point Colville on Lopez Island to Rosario Head on Fidalgo Island, and its northern boundary as a line from Point Migley on Lummi Island to the east tip of Puffin Island (just east of Matia Island) and then to Point Thompson on Orcas Island. Rosario Strait runs north-south between Lopez, Decatur, Blakely, and Orcas Islands on the west, and Fidalgo, Cypress, Sinclair, and Lummi Islands on the east.
- Open cluster (Wikipedia)
An open cluster is a type of star cluster made of tens to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and many more are thought to exist. Each one is loosely bound by mutual gravitational attraction and becomes disrupted by close encounters with other clusters and clouds of gas as they orbit the Galactic Center. This can result in a loss of cluster members through internal close encounters and a dispersion into the main body of the galaxy. Open clusters generally survive for a few hundred million years, with the most massive ones surviving for a few billion years. In contrast, the more massive globular clusters of stars exert a stronger gravitational attraction on their members, and can survive for longer. Open clusters have been found only in spiral and irregular galaxies, in which active star formation is occurring.