Archive for the ‘astronomy & space’ Category
The Economist has an interesting short article criticizing manned space exploration and praising the Obama administration for appearing ready to reprioritize America’s goals in space.
Mr Obama’s transition team had already been asking difficult questions of NASA, in particular about the cost of scrapping parts of the successor to the ageing and obsolete space shuttles that now form America’s manned space programme. That successor system is also designed to return humans to the moon by 2020, as a stepping stone to visiting Mars. Meanwhile, Mr Obama’s administration is wondering about spending more money on lots of new satellites designed to look down at the Earth, rather than outward into space.
These are sensible priorities. In space travel, as in politics, domestic policy should usually trump grandiose foreign adventures. Moreover, cash is short and space travel costly.
The article recommends using space probes and robots, like New Horizons (going to Pluto), Cassini (already at Saturn), and Mars Pathfinder to explore our Solar System.
While nothing is as cool as people in space, I wholeheartedly support investing our scarce space dollars in robotic and remote exploration instead of for crewed (“manned” is a bit androcentric) missions. For instance, NASA’s Moon Base proposal, despite being very modest, will still cost hundreds of billions of dollars. And it is unlikely that the knowledge and experience that we gain from such a base will justify the expense. The last Apollo missions were canceled and we haven’t been back to the Moon since the early 70s precisely because the place isn’t all that interesting. (For a good critique of NASA’s moon base idea, see “Moon Baseless“, an article by Gregg Easterbrook, who has been following the space program for decades.)
By contrast, excellent science is being done by our newest space probes and robots—and for far less money. New Horizons will have a total mission cost (from planning through the end of operations) of just $650 million; the total cost of the Cassini-Huygens mission is about $3.26 billion (including $1.4 billion for pre-launch development, $704 million for mission operations, $54 million for tracking and $422 million for the launch vehicle). Telescopes are also very cost effective. The Sptizer Space Telescope itself cost just $800 million and the planned James Webb Space Telescope will have a total cost (including planning, launch, and operation) of about $4.5 billion.
In short, for the cost of a Moon base we can explore the entire Solar System with probes and robots and explore the depths of space across all portions of the spectrum via orbiting and ground-based telescopes. If funding were unlimited things would be different; but it’s not and they aren’t. We have limited money for science, so we should spend it wisely.
Our galaxy, the Milky Way, appears to be about 50% more massive than we previously thought. A team of scientists lead by Mark Reid of the Harvard-Smithsonian Center for Astrophysics have conducted a detailed 3-D survey of our galaxy and determined that it’s diameter is about 15% greater than previously believed and it is spinning more rapidly than had been thought. The greater rotational speed indicates the presence of more mass, most of which is probably dark matter.
It is much harder to measure our own galaxy than those which are a million light years away because we’re embedded within it and can’t see the whole thing.
The new findings, which were presented today at the American Astronomical Society’s convention in Long Beach, California, mean that the Milky Way is about the same size as, not smaller than, our nearest large neighbor: the Andromeda Galaxy. Andromeda, a.k.a. M31, may be larger in volume than our home galaxy, but appears to only be about the same mass, likely due to differing amounts of dark matter between the two bodies.
The new mass data has another implication for Milky Way-Andromeda relations: the anticipated collision between the two galaxies may now happen sooner than previously thought. But don’t worry, it’s still 2-3 billion years in the future. The Sun won’t go nova for about 5-6 billion years, so it will still be around, as will the Earth. However, the expansion of the Sun will make it impossible for liquid water to exist on the Earth’s surface in only one billion years.
Galaxies collide are hardly unique occurrences in the universe. When they do happen, the stars themselves don’t collide, they’re too far apart for that to be likely; however, a star or star system might be ejected from it’s galaxy or, less likely, the orbits of planets within a star system might be disrupted. In any event, the gravity of the two galaxies will rip them apart until, millions of years later, they may form a new, bigger galaxy. It is thought that the Andromeda-Milky War collision will form a large elliptical galaxy, which some have preemptively dubbed Milkomeda.
While you’re waiting for the collision, note that 2009 is the International Year of Astronomy. Learn more about our endlessly fascinating universe by checking out some of the above links, or research any astronomical topics which are of interest to you. It’s your universe—learn about it!
The 2009th year of the common era is going to be delayed and its predecessor is being extended. For real. But just by a second.
As reported by MSNBC, the extra second, which is required to keep the time in sync with the Earth’s rotation, was ordered by the International Earth Rotation and Reference Systems Service (yes, that’s a real thing—here’s their website). Said rotation can vary slightly due to various factors, like the planet’s liquid core sloshing around and the gravitational effects of other Solar System bodies.
Leap seconds are added periodically; the last was inserted into 2005. Wikipedia has, unsurprisingly, more information on them.
Today NASA’s space probe MESSENGER made a flyby of the closest planet to the Sun, Mercury. The probe, whose name is both an acronym for Mercury Surface, Space Environment, Geochemistry and Ranging and a reference to Mercury’s role as the messenger of the Roman gods, took photographs of previously unseen areas of the planet’s surface and numerous other readings that scientists are now eagerly studying. This is the second of three flybys of Mercury, each of them serves to slow down the spacecraft to the point that it can enter orbit in 2011; it also got such gravity assists from Venus and from the Earth itself. Somewhat counter intuitively to a layman, going to Mercury is a lot harder than going to Mars, due to the very large change in velocity needed to enter orbit (or land on the planet, which no spacecraft has ever done and which is not part of MESSENGER’s mission). For more information on the mission, including many more photos, check out their official site.
The Economist has an excellent series of articles covering all aspects of the American presidential election. They also have a non-scientific online poll of their readers to see who would win the election if the electoral college were global and each country allocated its electors on a winner-take-all basis. Currently, Barack Obama is ahead 8375–15. McCain is ahead only in Georgia (the country, not the state), Macedonia, and Andorra. He is probably glad that this is just a poll of Economist.com visitors and not a real poll of public opinion in those countries, but, given that he’d probably still lose a worldwide popularity contest, he is probably very glad that this has no constitutional standing.
Speaking of the Economist, they have a thought-provoking article on “Data mining and the state.” It discusses how all the information that the government collects about us and processes can be used both to increase security and safety and to decrease our privacy and liberties. They discuss the future of such data mining and don’t pretend to offer clear answers as to when and how such technology should be used.
And speaking of the presidential race, linguists have analyzed the candidates’ remarks at the vice presidential debate (which I blogged about at some length here). They found that Palin spoke at the level of a 9.5th grader and Biden at that of a 7.8th grader. Palin, who spoke 5235 words, used the passive voice in 8% of her sentences; Biden spoke 5492 words and used the passive voice only 5% of the time. They both averaged 4.4 letters per word and were statistically tied on the length of their paragraphs; Biden’s averaged 2.7 sentences and Palin’s each had about 2.6 sentences. In his 1858 debates with Stephen Douglas, Abraham Lincoln spoke at an 11th grade level, they report—quite interesting, when you consider how much less education people had back then—though the level on which a person speaks doesn’t necessarily make what they say any better or clearer.
In wackier news, Virgin Galactic, Richard Branson’s company that will take paying customers into space, has rejected an offer of $1 million to use their spacecraft for filming two people having sex in space. “That was money we had to refuse, I’m afraid,” said company president Will Whitehorn (which, now that I’ve written it, sounds kind of like a male porn star’s name). If not for the fact that the company making the offer was unidentified, I would say that this was simply a publicity stunt. Virgin Galactic will probably begin flights in 2009 or 2010 and their spacecraft will carry six passengers in addition to two pilots. Tickets will cost $200,000. Even assuming that the $1 million was in addition to the $1.2 million that Virgin Galactic would pull in on a full flight it wouldn’t be worth the likely bad publicity that they would get. Besides, I’m sure a porn company could make much more than $1 million if they were the first to release a porn film of people having sex in zero gravity. Wait… maybe this is a publicity stunt, for Virgin Galactic. If so, it’s worked: I’m blogging about it.
The Russian Supreme Court has declared that Tsar Nicholas II and his family were killed illegally and are entitled to rehabilitation by the state. This involves formally exonerating them and declaring them victims of communist repression; over four million Russians have been rehabilitated since the collapse of the Soviet Union; The Tsar’s descendants have been trying for years to have him exonerated and were surprised at the ruling. Hopefully this will help Russia’s process of coming to terms with its past. However, I somehow don’t think that knowing he would be declared a victim of communist repression 90 years later would have been much comfort to Nicholas as he and his family were gunned down and bayoneted.
Congratulations to the People’s Republic of China, which has launched their third crewed mission to space and Zhai Zhigang, age 41, has successfully performed his nation’s first space walk. The spacecraft, the Shenzhou 7, has a crew of three astronauts—or taikonauts, as the Chinese call them (cf. cosmonaut). Besides China, only the United States and the Soviet Union/Russia have launched people into space.
China hopes to establish a space station by 2020 and also has plans to land people on the Moon and, eventually, Mars. They made the news last year when they shot down an old satellite in a test of their military abilities; this was largely seen as a provocative act and a possible threat to the United States, which maintains considerable assets in space for both communication, intelligence, and scientific purposes.
I am also struck, however, by the unoriginality of the China National Space Administration logo. Just look at it. Doesn’t it remind you of something? If you’re a fan of Star Trek, I’ll bet that it does. Compare:
Regardless of where the logo came from, Godspeed to the three taikonauts, Zhai Zhigang, Liu Boming, and Jing Haipeng.
Cosmologists have discovered that 700 clusters of galaxies are being pulled by a massive gravity source that is outside the observable universe.
Since the universe is approximately 13.7 billion years old we can see no more than about 13.7 billion light years in any direction. However, the entirety of the universe is larger—potentially unimaginably larger—than that due to an early expansionary phase in the universe in which space itself expanded at an incredible rate. The mass that is pulling on those galaxy clusters, each of which is made up of many galaxies, lies beyond our event horizon, outside the observable universe.
Some of the researchers hypothesize that the mega mass in question is the result of an area of the universe that did not undergo as extensive a period of hyper inflation, leading to a more dense area of space.
In these regions, space-time might be very different, and likely doesn’t contain stars and galaxies (which only formed because of the particular density pattern of mass in our bubble).
It could include giant, massive structures much larger than anything in our own observable universe. These structures are what researchers suspect are tugging on the galaxy clusters, causing the dark flow.
“The structures responsible for this motion have been pushed so far away by inflation, I would guesstimate they may be hundreds of billions of light years away, that we cannot see even with the deepest telescopes because the light emitted there could not have reached us in the age of the universe,” Kashlinsky said in a telephone interview. “Most likely to create such a coherent flow they would have to be some very strange structures, maybe some warped space time. But this is just pure speculation.”
Needless to say, scientists are very surprised at this unexpected finding.
Here are some of the news stories that have caught my attention in the past week. If you find any of them interesting, please comment!
The ongoing Census of Marine Life, an international effort to catalog all life in the oceans, has announced the discovery of hundreds of previously unknown species. They were found on various coral reefs and join thousands of other new species that the Census has discovered. Literally every where they look in the oceans, no matter how well previously explored, scientists are finding new species. The survey is expected to be completed circa 2010.
Speaking of the oceans and seas, hundreds of people on the Texas coast may soon lose their homes on account of Hurricane Ike and a 1959 state law that makes all coastal land between the low tide mark and the high tide mark public property and illegal to build upon. The hurricane has eroded many beaches severely, so many homes that were previously back from the water are now within that zone. Owners whose property is condemned by the state would probably get nothing in return, and it may take up to a year in some areas for the state to determine if the homes are indeed on public property now (it’ll take a while to see how the tides will act throughout the year). The law was last widely used in 1983 after Hurricane Alicia. I don’t think we should feel too bad for these people. “Every one of them was warned of that in their earnest money contract, in the deed they received, in the title policy they bought. … And whether you like it or not, neither the Constitution of the United States nor the state of Texas nor any law permits you to have a structure on state-owned property that’s subject to the flow of the tide.” These folks knew the risks and decided to take their chances. Unfortunately, they’ve lost their gamble.
On the other side of the pond, Harry Potter author J. K. Rowling has donated £1milllion (about $1.8 million) to the Labour Party, saying “I believe that poor and vulnerable families will fare much better under the Labour Party than they would under a Cameron-led Conservative Party.” This is the first time she has donated to the party and some cynics speculate that she is angling for a spot on the British honours list. Dame Rowling, perhaps? The Labour Party can probably use the money; they trail the Conservative Party in polls by about 12 points, though this is down from a 21 point defecit last month. Perhaps Gordon Brown’s declaration that he “wants to do better” as Prime Minister has helped his party out some? He doesn’t need to call elections until five years after the last ones, in May 2005, but they’re typically held a year before the parliament’s term expires unless the party in power is doing very poorly.
In American election news, despite none of the presidential debates having been held yet, millions of people can already cast their ballots in this years contests. In all, 36 of the 50 states have some form of early voting, though details vary by jurisdiction. In Virginia, considered an important swing state in the contest between Barack Obama and John McCain, citizens can already vote right now. In all, up to one third of voters are expected to take advantage of early voting or absentee ballots. Hopefully few of those voters get buyers remorse between now and election day. Of course, half the electorate gets buyers remorse after the election, so they’re really just doing that ahead of us too. (Note that I’m not posting a picture of Virginia’s state flag on account of it sucks really bad.)
Somewhat farther away, astronomers have identified the most massive star ever found in our galaxy. The previous record holder was about 83 times the mass of the Sun; this beast is 115 times the mass of our favorite star, and it happens to be orbited by the next most massive star ever discovered, which weighs in at 89 solar masses. The astronomers’ calculations have a margin of error of +/- 30 and 15 solar masses, respectively, for the two newly studied stars. Theoretically, the maximum size a star could possibly be is 150 solar masses. The larger a star is, the more quickly it burns out.
Some other astronomers have discovered a new galaxy, Segue 1, which despite orbiting the Milky Way was not previously studied on account of being only 1/1,000,000,000th as bright as our own galaxy. However, Segue 1’s gravity is about 1000 times greater than would be predicted based on it’s luminosity alone, indicating that it is chock full of way more dark matter than would be expected. Very little is known about dark matter, and there are still a few scientists who are skeptical that it exists, but the evidence is very strong. Most cosmologists think that dark matter plays an important role in the formation of galaxies, meaning we wouldn’t be here if it wasn’t. It is thought that there is approximately six times as much dark matter as normal matter in the universe, but that it only makes up about 23% of the universe, with almost all the rest being even more mysterious dark energy, which drives the expansion of the universe. In other words, we don’t know what 96% of the universe is. We’ll not run out of things to learn any time soon!
I hope this helps get your week off to an interesting start. Have a good one.
Back during the primary season Science Debate 2008 originally wanted to get all the candidates from both parties on the same stage to debate their respective views, approaches, and policies towards science-related topics. That didn’t happen. But what is about as good as could be hoped for is that both Barack Obama and John McCain have now submitted answers to questions they were given in a range of categories that together cover the spectrum of issues that face us and that require a scientific approach.
The 14 categories are: innovation, climate change, energy, education, national security, pandemics and biosecurity, genetics research, stem cells, ocean health, water, space, science integrity, research, and health.
The candidates’ written responses can be seen and compared side-by-side here. Highly recommended, even for those who have already made a decision about who to support.
Good news: it might be possible to travel faster-than-light! The bad news? Moving a cube that is just 10 meters on a side would take as much energy as would be gained if all of Jupiter’s mass (1.8986×10^27 kg) were converted into energy. That is a lot of energy and, as one scientist who is working on this idea put it, “We are still a very long ways off before we could create something to harness that type of energy.”
As I understand it, the theory, described in this news story, involves not moving an object through space, but manipulating space itself through the use of dark energy, which makes up about 74% of the universe’s mass-energy. This would involve similar processes as were at work in the early universe, just after the Big Bang, when space expanded faster than light, which, incidentally, moves 299,792,458 meters per second.
Well, the Solar System reforms of 2006, which I strongly supported, have not been as successful as I’d hoped. As many of you probably know, the International Astronomical Union then came up with the first formal definition of planet. The definition stated that a celestial object is a planet if and only if it:
- is in orbit around the Sun,
- has sufficient mass so that it assumes a hydrostatic equilibrium (nearly round) shape, and
- has “cleared the neighbourhood” around its orbit.
Furthermore, objects that met the first two criteria were termed “Dwarf Planets.” Pluto, Ceres (the largest inhabitant of the asteroid belt), and Eris were immediately classified as dwarf planets, and many other objects were candidates for the designation, once more was known about their sizes.
This resulted in there being eight planets in our Solar System: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune; Pluto was “demoted.” It was this last item, Pluto no longer being a planet, that has caused most of the popular discontentment and news stories over the reforms. Personally, this doesn’t bother me any and I find the use of school children, who are told to write letters to astronomers and museums complaining about “Pluto being taken away” to be totally shameless.
However, I do now recognize legitimate problems with the 2006 definition, as much progress as it represented. It is somewhat confusing that “dwarf planets” are not planets, though it sounds like they should be a subset thereof. Beside the other technical ambiguities, the whole debate is also something of a distraction, and draws attention away from the important things.
For these reasons, I am glad that the Great Planet Debate is resuming, according to ScienceNews.org, my previous support for the present definition notwithstanding. I now support redefining as a planet any object that:
- is in orbit around a star and
- has sufficient mass so that it assumes a hydrostatic equilibrium (nearly round) shape.
That would give us twelve planets. But, I would furthermore subdivide planets into major planets and minor planets, the former being those that have “cleared the neighbourhood” around its orbit and the later being those that haven’t. This would give us eight major planets–the current ones, or the old nine less Pluto–and several minor planets, including Ceres, Pluto, Makemake, and Eris–with more minor planets to come as we learn more about the thousands of objects in the Kuiper Belt.
I think this definition would be clear, for both astronomers and laymen, and would be very useful, which, after all, is the sine qua non of a good definition. The only problem is that the term “minor planet” is already in use; it is virtually synonymous with asteroid. Those objects, which will not be planets or minor planets under my suggested definition, will need to be called planetoids, asteroids, or any of many other suitable terms.
Finally, the definition will need to be tweaked to exclude brown dwarfs and to address the issue of so-called rogue planets–round objects that have been ejected from any stellar system–and binary planets, which would include systems like Pluto-Charon where the barycenter (gravitational center) of the system lies above the surface of both objects. This would make Charon and Pluto binary (minor) planets.
I think these reforms could greatly aid discussions about the fascinating Solar System in which we find ourselves situated. Eight (major planets) is great and more (minor planets) are good too!