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Monthly Archives: March 2011

H0 [news]

The latest measurement of Hubble’s Constant (Riess et al., 2011, ApJ, 730, 119, 2011; arxiv:1103.2976) — H0 = 73.8 ± 2.4 km s-1 Mpc-1

Dark Energy [Q&A]

Karthik asks, what is Dark Energy? To put it succinctly: I don’t know. At this point, it is just a name given to something that we don’t really understand. We know from looking at the brightness of Type Ia supernovae (which have very predictable intensities, so their apparent brightness is a good tracker of distance) […]

Is Dark Matter matter? [Q&A]

Karthik asks, if we convert some Dark Matter to energy, will that be energy as we know it, or Something Else™? The history of astronomy has been a series of shocks to the ego of mankind, as the importance of our place in the Universe keeps shrinking. First it turned out that the Earth was […]

Total Education [aim]

It is said that the goal of education at Harvard is to produce well-oblong individuals. That is, well-rounded, and with some aspects that they are particularly good at. This is the principle we are aiming for at CREATE Gurukula. Where they have the talent, students would be encouraged to develop it as much as they […]

distance to the Moon [try it]

How far is the Moon? You don’t have to look up the answer in a book. You can measure it yourself, and quite easily at that. You will need an accomplice however. For this, you will need some way to record the precise location of the Moon in the sky relative to the stars in […]

parallax [try it]

How do we know how far anything is? For nearby objects, we can pace off the distance, of course, but what about places we can’t walk to? How does your brain know that that door is 10 feet away without marking it off on a ruler? Suppose you are standing at point A (see figure) […]

solar differential rotation [try it]

The Sun is giant fluid ball of gas. It is not a solid body, and it does not behave like one. In particular, it rotates at different speeds at different latitudes. The website displays daily collections of solar images ranging from visible light photospheric images to magnetic maps to high-energy X-ray images of the […]

alien communication [try it]

Back in 1974, a message was beamed out from the Arecibo radio telescope towards the globular cluster M13. The hope is that it will be intercepted by some alien civilization that will then study it and learn some basic things about us. The full message, encoded as a string of two distinct patterns, is given […]

amateur X-ray astronomy [try it]

You don’t always need a telescope to do astronomy in your backyard. Data from all the great space-borne observatories (like Hubble, Chandra, Spitzer, etc.) are publicly available for people to peer through and analyze on their own. All you need is a computer and a functional internet connection. The only things stopping people is that, […]

exponential increase [try it]

Take a chess board and some rice. Put a grain of rice on the first square, Rook’s a1. Put two grains on the next one, Knight’s b1. Keep going down the row, doubling the grains at every square (4 on Bishop’s c1, 8 on King’s d1, etc), and continue the same way for row 2, […]