* Astronomy

Two of the most famous objects in the night sky are teaming up the next few evenings: the planet Venus and the Pleiades star cluster. Theyre well up in the west at nightfall. Venus is the brilliant evening star. The Pleiades, which is also known as the Seven Sisters, looks like a tiny dipper. Its just to the upper right of Venus this evening. The planet and cluster will be even closer to each other over the next few nights.

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The month of April holds the key to some exciting sky events that will add great satisfaction to the lives of observers. Make note of the fact that the first decent meteor shower of the year will take place on the night of April 22. This is the annual Lyrid meteor shower. Activity starts to build for observers looking to the northeast around midnight. By finding the bright star Vega in Lyra, you are looking at the region in the sky where the Lyrids are born.

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RU Virginis
The Mira variables undergo some of the most dramatic behaviour among all of the variable stars. For just that reason, they were among the earliest variable stars discovered and followed by astronomers trying to understand how our universe works. Four centuries after their discovery, the Mira variables remain one of the most challenging variable star classes to understand. All Miras are "dying stars", soon to shed most of their mass, leaving only a white dwarf behind. To fully understand these objects, we have to understand late stellar evolution, the physics of high-amplitude pulsations and convection, mass loss and stellar winds, and all of the microphysics and chemistry that ties them all together. Individual Mira stars are themselves in transition, but they also represent another cosmic transition in progress. Because the Mira stars are in the stage of their evolution during which most of their mass is returned to the galaxy through stellar winds and mass loss, they are a key mechanism for cosmic chemical enrichment for new generations of stars. Our understanding of how our galaxy and the larger universe are evolving depends in part upon the study of Mira variables.

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