As anyone who has read Hawking knows, you turn into spaghetti after you cross a black hole’s Event Horizon. The Illustrated Brief History of Time even has a picture of this.

It is common knowledge, of course, that you are doomed after you cross this boundary, and the only question is how much time you have left. In this sense, black holes are not all that different from HIV or cancers. However, unlike with HIV and cancer, the common answer to “what should I do” in the case of black holes has been “nothing, because just like in quicksand, the more you do the faster you get crushed by the singularity”.

A new study reported in Nature disagrees. It notes that the “do nothing” plan is only applicable if you have crossed the Event Horizon in zero velocity. In reality, however, one probably rarely does that (how often one actually crosses the Event Horizon altogether is another question). Instead, one tends to fall into a black hole with an initial non-zero velocity, and in that case the advice, it seems, is to counter your velocity so that it drops to zero.

In other words, if you were travelling north 50 km/h in your Ford Fiesta before you crossed the Event Horizon, you better hit the reverse, and speed just enough to attain a velocity of 50 km/h travelling south, so that your total velocity will be zero. It won’t save you, but it will buy you some extra time.

A new study of the Moon suggests that our natural satellite has an iron core. This apparently makes it more Earth-like than would probably be the case had the Moon been simply captured by the Earth’s gravitational field. As a result, the finding adds weight to the theory according to which the Moon was formed when a Mars-sized object slammed into our planet, tearing off a chunk that became the moon. See National Geographic for more information.

The Hubble Space Telescope, whom we can thank for our current estimations of the age of the universe as well as many ideas about its future — plus of course for all the pretty pictures — is getting a face lift in May 2008. NASA has finally decided to send a crew of seven astronauts to service the ageing telescope, which as a result ought to keep it functioning at least until 2013. Hurray, say I. (link)

The feud about the number of planets is starting to calm down, as New Scientist reports that the latest, and so-far best received, proposal is to demote Pluto and simply say that the definition of a planet is a significantyl large object which is “the dominant body in its orbital zone”.

This makes me wonder what happens if we discover twin planets, where two planets orbit one another, as well as their sun.

It also makes me wonder what the new mnemonic is going to be for the solar system. “My Very Excellent Mother Just Sent Us Nine Pizzas” used to be the trick to remember the order of the nine-planet solar system (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto), but obviously the sentence will not make any sense if Pizza is omitted. A recent Language Log article actually set out to construct a mnemonic for the original proposition that included thirteen planets: My Very Excellent Mother Could Just Send Us Nine Cheerleaders Playing Xylophones. I remain waiting for their suggestion about the non-Pluto mnemonic.

Again, I think this was already making the news rounds a while ago, but since BBC News has an article about it, let’s just go with the flow and note that a team of American astronomers think that they have discovered the gravitational signature of dark matter when observing the collision of two galaxy clusters.

For years now a war has been raging among astronomers about the definition of a “planet”. As BBC news reports, some sort of a solution is attempted next Tuesday, when experts gather in Prague to vote for a definition that would not only keep Pluto, but also include its twin Charon, the larger object 2003 UB313, as well as the largest asteroid, Ceres.

If the vote is passed, it would potentially open a can of worms, as the list of planets in our solar system would suddenly not be fixed, and new planets could be “discovered” as the new definiton would be applied to bodies found in the Kuiper belt. My opinion, therefore, would be to just keep the list of planets as it is, and decide that Pluto is on the list because of historical reasons. This may not be very scientific, but then again I’m not sure whether the whole issue is a scientific one, or rather one of purely linguistic nature.