Archive for the 'Astronomy' Category



Seeing the most distant galaxies in the Universe

The inset image at bottom right is one of the most distant galaxies in the Universe. Gravity from the galaxy cluster in the largest image magnified the light from that galaxy via gravitational lensing, making it barely visible. [Credit: NASA, ESA, W. Zheng (JHU), M. Postman (STScI), and the CLASH Team]

The inset image at bottom right is one of the most distant galaxies in the Universe. Gravity from the galaxy cluster in the largest image magnified the light from that galaxy via gravitational lensing, making it barely visible. [Credit: NASA, ESA, W. Zheng (JHU), M. Postman (STScI), and the CLASH Team]

If you’re like me, you’re watching the new Cosmos with Neil DeGrasse Tyson diligently these days. Last night’s show (at least for those of us viewing on Fox in the United States) largely dealt with my favorite topic: gravitation, and how it creates bizarre objects like black holes.

One very exciting image went by almost too quickly. It didn’t look like much — just a red blob of pixels — but what it represented is greater than its nondescript appearance would indicate. Those pixels are an image of one of the earliest galaxies in the Universe, and we’re able to see it because its light was magnified by the gravitation of a closer cluster of galaxies. This phenomenon is known as gravitational lensing, which is the topic of our next CosmoAcademy class!

In the course, we’ll explore how lensing works from Einstein’s general theory of relativity (without delving into the math). Then we’ll describe how astronomers use it to reveal information about both the object doing the lensing and the imaged entity, whether these systems are stars, galaxies, galaxy clusters, or light from the early Universe. It’s an exciting and important subject, so please enroll today!

The course begins next week on Tuesday, April 8. For more information, see the class page.

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