AAS #2: Black hole doesn't eat baby stars, and Milky Way more weighty

By Phil Plait | January 5, 2009 1:24 pm

1) Black holes succor!

So we live in a spiral galaxy, right? That means it’s a flat disk, with spiral arms, a bulge of stars in the middle, and right at the center sits a black hole — all big galaxies appear to have one. The monster in our middle tips the cosmic scales at over 4 million times the mass of the Sun. That sounds like a lot, but remember there are about 200 billion stars in the Milky Way, so in reality the black hole is 0.002% of the mass of the galaxy, more or less.

Artist’s concept of young stars near the galactic center.
Credit: NASA, ESA, and A. Schaller (for STScI)

Near the black hole, you’d think the environment is not exactly nurturing. The gravity of the hole is enormous, of course. Stars can orbit it in stable paths that last for billions of years, but big objects like gas clouds can be shredded; the black hole pulls on one side more strongly than the other, which can tear the clouds apart.

So we don’t expect to see young stars near the very center of the Milky Way — yet that is precisely what astronomers have found using the radio telescopes in the Very Large Array in New Mexico!

Young stars being born cry out in radio wavelengths, and the VLA is exceptional at precisely pinpointing post-partum protostars. The astronomers found two such young stars still in the act of forming. Incredibly, this means their cocoon of gas must survive being so close to the black hole — in this case, just seven and ten light years away! Since most gas clouds are light years across, this means these clouds must be smaller and more dense than usual.

This study means that stars can form in relatively hostile environments, and that in turn tells more about how stars form, which is cool, and what things are like very close to the maw of the supermassive black hole lurking at the galactic center, which is very cool indeed.

2) Our Galaxy is beefier than thought

Sitting as we do off to one side of the Milky Way, it’s really hard to get a good census of it. Dust clouds block our view, for example, and the Sun is rushing around the center of the galaxy along with the hundreds of billions of others.

Map of the Milky Way
Map of the galaxy, showing the center,
the arms, and the locations of the gas clouds
used to get the data. Our location is the red dot.
Credit: Robert Hurt, IPAC; Mark Reid, CfA,
NRAO/AUI/NSF

However, astronomers have used a collection of radio telescopes strung across the Earth to get better data than ever before on our home galaxy. And what they found is pretty interesting: we thought the Sun was going around the center at about 220 km/sec, but it turns out we’re actually moving at closer to 270 km/sec!

The speed of the Sun depends on the combined mass of all the stars, gas, and dust between us and the center. The gravity of all that stuff is what determines our speed. If we’re moving faster than we thought, then the galaxy itself must be more massive. This increase in speed indicates the Milky Way is actually 50% more massive than we previously thought!

That’s a big difference. That means we’re the equal of the Andromeda Galaxy, which we thought was the big boy of the local collection of galaxies. Now we don’t have to hang our head in shame any more.

Even cooler, the astronomers discovered the Milky Way appears to have four spiral arms, and not just two!

So we’re as massive as Andromeda, and we have four arms. Hmmmm. The obvious conclusion: we can easily take Andromeda on and beat it up! In a couple of billion years, we’ll get our chance, when the two galaxies collide and eventually merge. Sadly, after that, we’ll most likely be an elliptical puffball galaxy, with no arms at all. But until then, it looks like we’re king of the hill.

CATEGORIZED UNDER: Astronomy

Comments (35)

  1. Beelzebud

    Phil I remember reading a few years ago that our galaxy was thought to be a barred spiral. Is that still what we think it is, or is it just a spiral?

  2. Elmar_M

    I have always been wondering what a collision of Galaxies will actually do to the individual stars and starsystems. I mean with the large cosmic distances inbetween stars (at least “out” here) even within our galaxy, how great are the chances that it would actually have any notable effects on “us”?
    Just curious about the predictions for such an event.

  3. *sighs* I’ll call Eric Idle and tell him he needs to update the Galaxy Song.

  4. Charles Boyer

    Well, none of this matters since we’re all a-gonna-die (!!!11!1!!) just before Christmas in 2012 when the comet-planet Niburu comes along and wipes out the Earth. Can you tell I have had four different people ask me what I thought about the Mayan Calendar / Nostradamus show on History Channel last night?

    Seriously, this seems to be a fairly radical shift in our cosmological self-identity mass-wise, but I thought the four arm idea was not so new: the 3-kpc and Perseus Arm, Norma and Cygnus Arm, Scutum-Crux Arm, Carina and Sagittarius Arm are the four, right?

  5. @Elmar_M: For this post, I’ve (hopefully) directed my website URL to a video that shows a simulated collision of the Milky Way and Andromeda as seen from Earth. While we might not directly collide with other heavenly bodies, the effects could still be profound.

    (It’s a largish 27 MB MOV file.)

  6. Tiki Idyll

    The Milky Way has sprouted another two arms!? Oh no! PZ is attempting to convert the entire galaxy into a cephalopodic minion to obey his every whim! Save us, Dr. Plait!

  7. i can’t possibly keep track of how many arms the milky way “has”. didn’t it just go down from 4 to 2 last year? or was it up from 3 to 4? or was that the year before? seems a little like

    def number_of_arms_in_milky_way(year):
    return int(rand(0,8))

  8. Old Geezer

    Not being an astronomer, help to understand how a 23% increase in speed (220 to 270) translates to a 50% increase in apparent mass.

  9. @BA “Even cooler, the astronomers discovered the Milky Way appears to have four spiral arms, and not just two!”

    Isn’t that the reverse? They’ve recently discovered that there are just 2 arms?

    http://www.livescience.com/space/080603-aas-spiral-arms.html

    “New Images: Milky Way Loses Two Arms
    By Jeanna Bryner, Senior Writer
    posted: 03 June 2008 01:01 pm ET

    ST. LOUIS — For decades, astronomers have pictured our galaxy as sporting four major, spiral arms, however new images effectively sever two appendages, revealing the Milky Way has just two major arms.

    “We’re not proposing that they change the positions of the arms,” said Robert Benjamin of the University of Wisconsin, Whitewater. “What we’re proposing is a change in the emphasis of the arms.” Benjamin will present his team’s results today here at a meeting of the American Astronomical Society (AAS).

    The results are among a handful of presentations at the meeting to paint an evolving picture of our galactic home base.

    For instance, other results presented here by Thomas Dame of the Harvard-Smithsonian Center for Astrophysics (CfA) this week suggest a completely new arm of stars wraps around one side of the galactic center. This new arm is a virtual twin of a known arm on the near side of the galactic center. And another group led by Mark Reid of CfA has identified with more accuracy the location and relative distances of the stars within the spiral arms.

    The Milky Way debuted as a spiral celebrity in 1951 when astronomical morphologist William Morgan of the Yerkes Observatory presented his results showing the galaxy’s three arms of hot stars, which he were then named Perseus, Orion and Sagittarius.

    “Those were the first three arms of the spiral galaxy,” Benjamin told SPACE.com. “Actually, he got a standing ovation at the AAS meeting, which is something I’ve never seen.”

    Beginning in the 1960s and through the 1980s, several groups of scientists used radio astronomy to map out the Milky Way’s structure, coming up with various results on how the spiral arms looked and the number of arms.

    “For years, people created maps of the whole galaxy based on studying just one section of it, or using only one method,” Benjamin said. “Unfortunately, when the models from various groups were compared, they didn’t always agree. It’s a bit like studying an elephant blind-folded.”

    The galactic image that stuck, Benjamin said, was one with the four spiral arms, now called Norma, Scutum-Centaurus, Sagittarius and Perseus. Our sun lies near a small, partial arm called the Orion Arm, or Orion Spur, located between the Sagittarius and Perseus arms.

    The new survey of an extensive swath of the Milky Way was done with NASA’s Spitzer Space Telescope, which detects infrared light. All objects that emit any heat can be seen in infrared, and this wavelength penetrates dust, so the new mosaic includes 800,000 snapshots and more than 110 million stars.

    Using a star-counting method, Benjamin and his colleagues noticed an increase in the number of stars in the direction of the Scutum-Centaurus Arm, but not in the direction of the Sagittarius and Norma arms. (The fourth arm, Perseus, wraps around the outer portion of our galaxy and cannot be seen in the new Spitzer images.) The two major arms, according to these findings, are the Scutum-Centaurus and Perseus arms.

    The findings confirm an earlier observation by a team of astronomers, making a strong case that the Milky Way has two major spiral arms, a common structure for galaxies with bars. These major arms have the greatest densities of both young, bright stars and older, so-called red-giant stars.”

  10. @Old_Geezer “Not being an astronomer, help to understand how a 23% increase in speed (220 to 270) translates to a 50% increase in apparent mass.”

    v-orbital = sqrt(G * M / r)

    where v-orbital is orbital velocity of the sun, G is the gravitational constant, M is the mass of the galaxy internal to the sun’s orbit, and r is the distance of the sun from the galactic center. Solving for M we have:

    M = (r / G) * v-orbital^2

    So increasing v-orbital by 1.23 results in an increase in M of 1.23^2 or 1.51. There’s your 50 percent increase.

  11. Old Geezer
  12. Tom– well, my post was getting long so I left out some details. There are appear to be two arms with older stars, and four arms that are creating stars. It’s unclear why this would be. The press release linked above has a few more details though not much to be honest.

  13. “Our location is the red dot. ”
    Hang on, that’s in the middle. Aren’t we out on one of the arms?

  14. I usually don’t do this, but let me interject an OT essay in honor of the recent 100th anniversary of the publication of Percival Lowell’s book “Mars as an Abode of Life”. It also provides a lot more detail concerning a dispute I was having with someone on one of the previous topics:

    Ages of Hope, Ages of Doubt (part 1)

    In addition to 2008 being the 40th anniversary of the famous Apollo 8
    Christmas broadcast from lunar orbit, it is also the 100th anniversary of the publication of the book “Mars As the Abode of Life” by the American astronomer Percival Lowell (1855 – 1916). In 1877 the Italian astronomer Giovanni Schiaparelli reported seeing “canali” on the surface of Mars. The word “canali” means channels in Italian but it was mistakenly translated into English as “canals” which implied that they were some kind of engineering feature.

    Lowell picked up the story of canals and ran with it, devoting the last twenty years of his life to observing Mars and its canals. Lowell constructed an observatory in Flagstaff, Arizona expressly for the purpose of observing Mars. Over the course of many years Lowell maintained that he could see dark canals forming a network over most of the surface of Mars. The fact that other astronomers looking at the same planet did not see these canals left him undaunted.

    Lowell speculated that an intelligent race of Martians had built a vast network of irrigation canals in a desperate attempt to bring water from the Martian polar regions to the equatorial region of Mars. Unlike the fictional Martians in H.G. Wells’ novel “The War of the Worlds”, Lowell envisioned his Martians to be a more-or-less benign race fighting a desperate battle against the gradual desiccation of their planet.

    Soon enough the entire Lowellian fantasy of Martian canals would evaporate, especially when space probes from Earth finally arrived in Martian orbit by the middle of the 20th century. I am old enough to still remember textbooks from the 1960′s in which the seasonal color changes in the surface of Mars were attributed to the possible growth and decay of vegetation, so we are not far removed from the age when Mars was thought to contain canals. Lowell’s Martian canals would mark one of the last times that a scientist of any substantial stature would claim to have proof of extraterrestrial life.

    The question of whether life exists beyond the earth is not new. It goes back centuries or perhaps even millennia. No other scientific question has had as many twists and turns in the tale with scientific sentiment shifting back and forth between optimism and pessimism as new discoveries were made and old assumptions were challenged. And perhaps no other scientific question has remained unresolved up until today with no firm conclusion either way and no hint of when such an answer might come.

    So I thought I might break the scientific consensus into different historical periods. Periods when the question “Is there life beyond Earth” was answered affirmatively shall be called optimistic ages, and periods when the question was answered negatively shall be called pessimistic ages.

  15. Ages of Hope, Ages of Doubt (part 2)

    1st Pessimistic Age: c. 150 CE – 1543

    Claudius Ptolemaeus (or Ptolemy) was a Greek astronomer of the 2nd century CE. He published his famous work in astronomy, called the Almagest, in c. 150 CE. It set out an Earth-centered universe in which the five known planets (Mercury, Venus, Mars, Jupiter, and Saturn) plus the sun and the moon revolve around a stationary earth. Coupled with Aristotle’s notions of physics the geocentric model of Ptolemy would dominate Western thinking for more than a millennium. According to Aristotelian physics, matter on the earth is composed of four elements: earth, water, air, and fire. But the celestial realm is composed of a separate 5th element, the ether. Thus, since the planets are not composed of earthly elements nothing like earthly life can exist there.

    The planets were thought to be lights in the sky, not places that one could visit. Thus, extraterrestrial life was unimaginable using Aristotelian cosmology. All of this was about to change. In 1543 the Polish cleric Nicolaus Copernicus published his famous treatise which proposed a sun-centered cosmology.

  16. Juan C

    @”Tom Marking”

    The report of two arms was frankly bogus. They were using IR data. IR data tends to see the old, low mass (very cool) stars, not the young stars that delinate the spiral arms. They were seeing the fossil arms before. I think this “discovery” of four arms is frankly what is referred to in sci-fi as a ‘retcon’. They are fixing the error they introduced earlier. :)

  17. Ages of Hope, Ages of Doubt (part 3)

    1st Optimistic Age: 1543 – c. 1850

    Copernicus’ cosmology still retained the crystalline spheres of Aristotle, only now they were centered on the sun, not the earth. The outer sphere of fixed stars was retained and held to be immutable. This notion was shattered by Tycho Brahe who observed a guest star (i.e., a supernova) in the year 1572 thus proving that the fixed stars were not immutable. Furthermore, he measured the path of a comet a few years later and proved that it must have been traveling across the crystalline planetary spheres assuming they existed at all. Tycho had killed the crystalline spheres of Aristotle.

    In 1576 the English mathematician Thomas Digges published a book in which the sphere of fixed stars was abolished. Instead, space was imagined to stretch infinitely in all directions. A few years later the Italian cleric Giordano Bruno extended Digges’ idea to include an infinity of stars scattered throughout space, with each one having its own retinue of inhabited planets. For his trouble Bruno was burnt at the stake by the Catholic Church in the year 1600.

    During the 17th century the concept of inhabited worlds really took off. In the 1686 book “Plurality of Worlds” the French author Bernard le Bouvier de Fontenelle argued that both the moon and the planets were inhabited. The argument went like this. We know that the moon has many similarities to the earth – it has mountains and what were interpreted as seas at that time. Therefore if it is so geographically similar to the earth, it must also be biologically similar. And the same holds for all the planets.

    A similar book entitled Cosmotheoros by the Dutch astronomer Christian Huygens was published in 1698 after his death. Similar arguments to those used by Fontenelle were expounded by Huygens, but in addition he used the theological argument that the Creator would not have gone through the trouble of creating planets without bothering to populate them with animals and plants. This was, of course, before the age of Darwin and natural selection.

    In addition, by 1755 the German philosopher Immanuel Kant had developed the nebular hypothesis for the formation of the solar system. This idea seemed to imply that planetary systems were a common place feature around most stars. The idea would not be confirmed for another 240 years.

  18. Ages of Hope, Ages of Doubt (part 4)

    2nd Pessimistic Age: c. 1850 – 1953

    Several factors combined to bring the 1st Optimistic Age for extraterrestrial life to a close. In 1837 the German astronomers Johann Heinrich von Madler and Wilhelm Beer published a book about the moon in which they showed that it lacked both oceans and an atmosphere. Ironically this was only two years after the Great Moon Hoax in which an intelligent race was claimed to have been discovered living on the moon. Without air and without water the moon suddenly became a less inviting place as far as living things were concerned.

    In 1851 the British philosopher William Whewell questioned the universality of life throughout the solar system. He claimed that the outer planets of Jupiter, Saturn, Uranus, and Neptune were too far from the sun and thus too cold for life to exist. Venus and Mercury were too close to the sun and thus too hot for life. The concept of circumstellar habitability had begun.

    To make matters worse, problems had begun to surface in the nebular theory of solar system formation. It soon became apparent that the planets contained 98 percent of the solar system’s angular momentum whereas the sun contained just 2 percent. This should not have been the case if the sun had contracted via gravitational collapse. Just like a skater bringing in her arms and thus rotating faster and faster, the sun should have sped up its rotation as it condensed from the solar nebula. It should be rotating much faster than its current 27-day rotation period. What to do about it?

    Around the year 1900 the British astronomer F.R. Moulton and his colleague T.C. Chamberlain developed the catastrophist theory of solar system formation in which the solar system formed due to a near approach of another star which sucked material off the sun which later became the planets. If true then it would mean that the solar system was the luckiest of flukes – perhaps a one in a million odds type of phenomenon. Of course that would mean that planetary systems around stars would be extremely rare and so would extraterrestrial life.

    Of course, not everyone marches to the tune of the age he/she finds themselves in. Percival Lowell was one exception, but by the opposition of Mars in 1907 when Lowell’s sightings of canals on Mars were not confirmed by other scientists, he was distinctly in the minority of scientific opinion. Alfred Russell Wallace, the co-discover of the theory of evolution by natural selection, published a book in 1897 in which he demolished Lowell’s claims for an intelligent race on Mars. The temperatures on Mars were much lower than Lowell had claimed, the atmosphere was much thinner, and more importantly, spectroscopic measurements had failed to detect any
    water vapor in the Martian atmosphere. Mars seemed to be a dead world. Case closed.

  19. Ages of Hope, Ages of Doubt (part 5)

    2nd Optimistic Age: 1953 – present

    It was an experiment in organic chemistry conducted at the University of Chicago in 1953 which brought the 2nd Pessimistic Age to a close. Stanley Miller and Harold Urey pumped a mixture of gases into a spherical flask in order to simulate the atmosphere as it had existed on the primitive Earth. The gases consisted of water vapor, methane, ammonia, and hydrogen, all thought to have existed on the primitive earth. An electric spark was introduced inside the flask, simulating lightning on the primitive earth. After running the experiment for several weeks, brownish streaks appeared on the inside of the flask. When examined this brownish material consisted of a variety of organic compounds, including amino acids which are the building blocks of proteins.

    The stuff of life had been generated under circumstances thought to be
    similar to what had existed on the early earth. If amino acids could be produced so easily in only a few weeks in a laboratory experiment, then there might be no limit to what Mother Nature could do operating over the course of millions of years and over the surface of an entire planet. Given the right ingredients life seemed an inevitability.

    During the 1930′s the American astronomer Otto Struve discovered an interesting correlation between the rotation rate of a star and its spectral type. For stars of spectral type O, B, A, and F the rotation
    velocity is high (typically greater than 20 kilometers per second). For stars of spectral type G, K, and M the rotation velocity is low (typically less than 20 kilometers per second). Where had the angular momentum of the G/K/M stars gone? One explanation was that it had gone into the formation of planetary systems. This was the first astronomical evidence that the formation of planetary systems might be a common occurrence throughout the cosmos.

    By the 1970′s the nebular theory of solar system formation had been resurrected. The previous problem with the transfer of angular momentum from the star to its planets was solved by introducing magnetohydrodynamics into the mix. All that remained now was the detection of real planets orbiting stars. This discovery was a long time in coming. After many false starts such as the spurious detection of a planet around Barnard’s star in the 1960′s, the first exoplanet orbiting a main sequence star was detected in 1995 by the Swiss astronomers Michel Mayor and Didier Queloz. The planet they discovered (it’s official name is 51 Pegasi b but it is unofficially
    called Bellerophon) orbits once around its star in only four days at a distance of only 0.05 astronomical units. It was the first of the many so called “Hot Jupiters” to be discovered. As of 2008 more than 200 exoplanets have been discovered which means that planetary systems are truly commonplace features of stars throughout the cosmos.

    In 1959, only six years after the Urey-Miller experiment, Philip Morrison and Giuseppe Cocconi of Cornell University proposed the first microwave search for extraterrestrial intelligence. They recommended that the 21-centimeter band of galactic hydrogen emission be the frequency of choice for such searches. And thus, SETI (Search for ExtraTerrestrial Intelligence) was born. The very next year in 1960 Frank Drake, also of Cornell, performed the first actual SETI search called Project Ozma. Drake observed two nearby stars, Tau Ceti and Epsilon Eridani, at the 21-centimeter hydrogen frequency. After a false alarm which turned out to be a transmission from an aircraft, no signals of extraterrestrial origin were reported. The SETI search had begun in earnest and continues until today.

    Thus, within only a few short years, the 2nd Optimistic Age was in full swing and continues until today. It has been bolstered from time to time by major discoveries such as the discovery of “black smokers” on the ocean floor in 1977, opening up a whole new realm for earthly life to exist. During the 1970′s biologists were discovering that life was much more robust than they had previously believed. It could exist in the most extreme environments such as high temperature hot springs, the high pressures of the ocean floor, high salinity pools, and the high radiation environments surrounding nuclear reactors. It was also at this time that the biologist Carl Woese reorganized the family tree of life and created the new category of Archaea. It turned out that Archaea contained many of the newly discovered microorganisms which seemed to thrive in extreme environments. And Archaea seemed to be an ancient grouping of life forms, perhaps more closely related to the original life forms that arose on the Earth.

    In the meantime geologists were pushing the age of the first life on Earth ever backward, with confirmed fossil stromatolites dated to 3.5 billion years old. There is even more recent evidence that might push the origin of life back to 3.8 billion years ago or even older, which was a time when the earth was still being bombarded by large planetesimals. If life could have originated under such hostile circumstances back then, then it seemed likely that it could have originated independently on many different worlds.

  20. DrFlimmer

    I guess there will always be “new” findings how the milky way actually looks like. It’s just our disadvantage sitting in it. Last year we just got 2 arms – now we have 4 (or probably 6 as Phil mentions above). It’ll be interesting how much we’ll have next year…
    I think it is more interesting that the sun “accelerated” by about 50km/s. That’s quite a jump!
    And even more interesting is the first part of this post! Stars created next to a SMBH! That is cool! Tidal forces are quite strong if even our little moon can rise the oceans! So being so closed to a SMBH and not being ripped apart is really an accomplishment. Probably there are stars created even closer to the hole. I guess there is work to do for some theoretical guys.

  21. Ages of Hope, Ages of Doubt (part 6)

    A 3rd Pessimistic Age?

    Even though we are living in the 2nd Optimistic Age, already there are
    unsettling signs that we may be headed for yet another Pessimistic Age. Perhaps the first sign of this was the 1976 landing of the Viking spacecraft on the surface of Mars. Although the science results of the two Viking spacecraft were indeed tantalizing, they stopped short of providing conclusive evidence for the existence of life on Mars. Several additional Martian spacecraft that have landed on Mars in the years since have also failed to provide any evidence for the existence of life on Mars, either in the past or now.

    The original hoopla over the ALH 84001 meteorite back in 1996 has now died down. There is no scientific consensus that ALH 84001 contains unmistakable evidence of early Martian life, despite the initial claims of NASA’s David McKay. The trail seems to have gone cold with perhaps a Martian return sample mission being required to resolve the dispute once and for all.

    Also, it has now been almost 50 years since the first SETI search and no bona fide signal has been detected. The sensitivity of the search has been improved by many orders of magnitude, and still the best candidate signal is the so called “Wow Signal” detected by the Big Ear radio telescope of Ohio State University back in 1977. So far this signal has never repeated and maybe it never will. With every year that goes by with no confirmed SETI signal the parameters of the Drake Equation must continue to shrink, and the farther we slip towards a Pessimistic Age.

    How long will this oscillation between optimism and pessimism continue? It seems likely to continue until some definitive evidence can answer the question one way or the other. How long it might take for that evidence to arrive is anyone’s guess. It might arrive tomorrow, or it might arrive one thousand years in the future, or it might never arrive in which case we will kept guessing perpetually.

    I hope you have enjoyed this brief foray into the history of perhaps the greatest question that humanity has ever asked: Are we alone in the universe?

  22. @Jivlain ““Our location is the red dot. ”
    Hang on, that’s in the middle. Aren’t we out on one of the arms?”

    They actually mean the red dot which is about 75% of the way from bottom to top and 50% of the way from left to right, not the red asterisk looking thing in the center of the picture.

    Reading the article they claim to be able to get very accurate distance measurements from stars that are operating as masers (i.e., producing coherent microwaves). I always thought they needed a mission such as TAU (Thousand Astronomical Units) to improve the trigonometric parallax measurements by a factor of 1,000. I wonder why they can’t get a super-accurate distance to the central black hole using the maser technique, say 25,694.3 ly or something like that. Overall the article left me with more questions than answers.

  23. Elmar_M

    Yeah, I know that colliding galaxies do cause quite a bit of disturbance and that is to be expected (I suppose gravity is the cause of that), but I do not quite understand what that would mean for our solar system (seen as an entity).

  24. Naomi

    I have nothing intelligent to add, I just want to go cooooooooooool.

  25. Brian

    Elmar_M: Actually, there’s a book you can buy that has a whole chapter devoted to that very subject … hmmmm … what was that book’s title again? Fatality from the Firmament? Extermination from the Empyrean? Woe from the Wild Blue Yonder?

    The executive summary: Anything from having one or more planets kicked out of the solar system, to the solar system kicked out of the galaxy, to getting completely blasted when the two supermassive black holes merge, to not much of anything really.

  26. Brian

    But as to the main subject of this post, I wholeheartedly second Naomi.

  27. @Tom Marking: Ah, I see it now. Thanks for the clarification. I can’t connect to the embiggening page, for some reason.

  28. Sir Struggle

    On the subject of lack of enthusiasm for the space program…..

    Getting to to the moon was such a big achievement (worldwide even) that once that boundary was reached, everything else seemed (seems) tiny in comparison. “We went to Mars” you might say. “So what” , one might retort, “We went to the moon 40 years ago.” In the scale of things, nothing that we accomplish is a big deal anymore.

    This is perfectly natural and understandable. 40 years ago, a spacecraft guided by 1′s and 0′s with less computing power than my car stereo found its way onto the moon, forever an icon. Unless someone finds some way to emulate sci-fi and transport people, or travel faster than light, this achievement will be the pinnacle of mankind’s space exploits until long after we’re all gone.

    I have understood this for years and have no problem with “only” GPS, Hubble, Direct TV, or the many other discoveries Space exploration has provided me with as proof of the viability of NASA (don’t forget the pretty pictures). The public, on the other hand, needs daily reminding or else it becomes a waste of money better spent on gadgets sold by Billy Mays at 2 a.m.

    NASA’s problem (other than the under-reporting of what it actually needs to do something for its budget) is PR. I still think it should get together with Discovery Channel and make a space channel (hell there’s a military channel, and planet green. I think they could fill the time at least as well as tommy lee and ludicrous do on PG, especially with all the advances in private industry)

  29. Hugo

    How certain are we about the position of the Sun in the Milky Way? Isn’t also possible that instead of the galaxy being more massive than previously thought, we just happen to be closer to the center, closer enough to justify the extra speed?

  30. Winter Solstice Man

    That artwork of young stars in the galactic center was recycled from a news item a few years back about young stars in the center of the Andromeda Galaxy.

    Not that it matters, probably.

  31. Elmar_M

    Brian said:
    “Anything from having one or more planets kicked out of the solar system, to the solar system kicked out of the galaxy, to getting completely blasted when the two supermassive black holes merge, to not much of anything really.”

    Those were pretty much my guesses as well. So I guess one can say: we do not know ;)

  32. amphiox

    The solar system getting kicked out of the galaxy, or having its orbit shifted in whatever way large or small, in most likelihood wouldn’t have that big an impact on the earth itself per se, except to change the view of the night sky. (We’d of course be seeing two Milky Way-like bands in the sky in the run-up to the collision).

    Of course, I think the latest consensus is that earth wouldn’t be habitable anymore by the time this happens, not to say that humans might not still be around elsewhere by then.

  33. How do they know the increased Solar orbital velocity isn’t just a result of the sun being at the periglacticon of an elliptical orbit?

  34. WJM

    I love how we’ve been living in this galaxy for billions of years, and yet we’re still discovering new things about it!

  35. Autymn D. C.

    I see five arms in the map. Our “partial arm” looks broken by Sagittarius. Our half thus has Norma outermost, Perseus, Cygnus-Orion innermost; the other half has Sagittarius-Carina outermost, Scutum-Crux-Centaurus.

    “The planets were thought to be lights in the sky, not places that one could visit.”

    If they were stones they would fall back tom Earth, wriht? Which was why meteòrites in the 1800s were still denied?

    “How do they know the increased Solar orbital velocity isn’t just a result of the sun being at the periglacticon of an elliptical orbit?”

    They didn’t say the span was any shorter.

    I proved the black hole is as fake and wrong as the unicorn:
    http://google.com/groups?q=Autymn+-autumn+doubt+deathblows
    http://groups.google.com/group/sci.physics/browse_frm/thread/73daba2d40dc8cfc/c44cda8b8e572d77?

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