Space is empty… almost.  When we say vacuum, we mean space that is devoid of matter, but interestingly, creating a real vacuum on earth in a laboratory has been impossible.  Just how empty are different degrees of vacuum? How empty are the depths of space?  Between planets? Between stars? Between galaxies? We can go through a quick scale of emptiness.  As it turns out, space beats out our best efforts by a longshot.

Table borrowed from http://en.wikipedia.org/wiki/Vacuum

There are some surprising conclusions.  The commercial vacuum is ironically not much of a vacuum at all; it only reduces pressure by about 20%.

Mars’ atmosphere is 1/100th the density of Earth’s.

The moon does have an atmosphere, and it gives about the same surface pressure as our BEST vacuums on earth.

Interplanetary space is densely populated in comparison to the cold, dark space between stars and galaxies.

The quantum description of the vacuum is quite different, but we can save that for later.

Öpik, E. J. (1962). “The lunar atmosphere”. Planetary and Space Science 9 (5): 211. Bibcode:1962P&SS….9..211O. doi:10.1016/0032-0633(62)90149-6.

Chambers, Austin (2004). Modern Vacuum Physics. Boca Raton: CRC Press. ISBN 0-8493-2438-6. OCLC 55000526.^{[page needed]}

University of New Hampshire Experimental Space Plasma Group. “What is the Interstellar Medium”. The Interstellar Medium, an online tutorial. Retrieved 2006-03-15.

Scientist have used the Hubble Space Telescope(the one that gives you all those cool pictures of distant Nebulas and Galaxies) to extend our ability to accurately measure the heavens by 10 times.  The new technique, called spatial scanning, is combined with Astronomical Parallax, the long used technique, to increase our ability to measure astronomical objects astronomically.[ sorry 🙂 ] Astronomical parallax is a technique similar to the parallax used by land surveyors on Earth. It involves taking pictures of a distant at 2 different locations, and using their apparent position and some trigonometry to calculate distances. Since Astronomical distances are so vast, we have to take pictures on the other side of the Sun instead of just a couple of miles away. By combing this technique with the new technique of Spatial Spanning, scientist are improving our ability to measure, and thus our understanding, of the the Universe. What is so amazing is that its the Hubble Space Telescope at it again. It was initially launched in 1990, and the last servicing of the telescope came in 2009, yet it still continues to provide us with invaluable scientific data. Talking heads like to complain about space expenses, but clearly, we are getting our moneys worth with this one. It has long served as a public resource, and anyone can apply for Hubble time. There are also still major missions planned with the telescope, and it is expected to continue to operate until about its 30th birthday.

On April 14th, Space X’s Dragon spacecraft launches towards the International Space Station. If you remember from last year maybe, Space X became famous for being the first private space company to be contracted by NASA to deliver cargo to the ISS. This comes as a relief to space enthusiast and normal people who were sad, and distressed, as Congress continually cut funding from NASA on a yearly basis. Now that the private sector has jumped in on space exploration, the stalling of humans discovery of the natural world has come to an end. The experiment for which Space X has been called upon this time is both very interesting and vital to the future of manned exploration. See, the thing is, space travel isn’t all that healthy. Our bodies simply made to not feel the relentless tug or gravity, and the constant free fall of orbit does some weird things to Astronauts. Coupled with the much larger amounts of radiation received by our zero G scientist flying above us, perfectly healthy astronauts can return to Earth a bit out of whack. But this shouldn’t worry you, overall they’re fine. However these effects provide us with data to study the way humans are affected by space travel, and this knowledge will help us out in the long term when the human race turns its attention to the outer reaches of space. Dragon is also bringing some plantlife up to the station, that the astronauts will be growing in order to further study plant growth in space. Both of these studies could ultimately be vital if you believe like me that our long term survival might be contingent on our ability to blast of this, our most precious of rocks and land on a new one, however far away.

http://www.sciencedaily.com/releases/2014/04/140414103310.htm  

While doing some readings for my most recent blog post, I came upon an article written in 2005 that anticipated results from a new NASA project with an anticipated launch date in 2010. Being that it is 2014, I assumed that there would be some results available from that project. However, with a little more reading, I discovered that project has been postponed until 2034 due to budget constraints. That got me thinking about the future of NASA and its role moving forward.

The first noticeable trend is that manned spaceflight is probably not reasonable at this point and may become obsolete moving forward. Since man landed on the moon, unmanned spacecraft have become exponentially more useful. As Charles Seife at Slate points out, the International Space Station has essentially been fruitless in terms of reaching its research goals. In contrast, unmanned spacecraft have been collecting Nobel Prize-winning data for years. Furthermore, 4% of US astronauts have perished on their missions, which is in many ways an inexcusable number. Until it becomes feasible to place men on Mars, there may not be manned space-travel for these reasons.

Image Source: NASA Budget

Maybe even more troubling, the projected NASA budget for 2015 shows a 24% decrease in the education sector. Arguably one of NASA’s most lasting impressions on the public has been inspiring the next generation of scientists and innovators. Space has always been able to capture the human imagination, and there is no exception when it comes to schoolchildren. As Neil deGrasse Tyson puts it: “If I say, ‘Design me a plane that’s more fuel-efficient, because the country needs that now,’ you’re not going to get any truly transformative, innovative solutions. Instead, if I say, ‘Who wants to build an air foil that’ll navigate the rarified atmosphere of Mars?’ or ‘We’re about to go to Mars. Who wants to study life forms that are yet to be understood that we may discover?’ I’m going to get the best engineers, I’m going to get the best biologists.” Space and its frontiers have been able to bring about the best in human innovation for generations, and if NASA loses the capability to inspire students across the country, irreparable damage may be done to the next crop of engineers and explorers.

Sources and Further Reading:

http://www.theatlantic.com/technology/archive/2012/03/neil-degrasse-tyson-how-space-exploration-can-make-america-great-again/253989/

http://www.slate.com/blogs/bad_astronomy/2014/03/05/nasa_budget_2015_more_cuts_more_politics.html

http://www.planetary.org/blogs/casey-dreier/2014/0314-official-statement-on-nasas-2015-budget.html

http://www.slate.com/articles/health_and_science/mysteries_of_the_universe/2014/02/nasa_s_mission_its_search_for_meaning_has_limited_its_science_and_damaged.2.html

Ever heard of Nicolaus Copernicus. Of course you have, he’s the 16th century mathematician and astronomer who proposed the Heliocentric model. In fact, Copernicus wasn’t the first to propose the Heliocentric( or Sun at the center) model of the solar system. Astro-hipsters will recollect all the way back in the 3rd Century BC, before their was even the pope to rebel against, Aristarchus of Samos was telling folks that the Earth rotated around the Sun and not the other way around. So why are we talking about long dead people who proposed very obvious theories. Well, despite the new Geocentric movie that is coming out (check it out if you haven’t already, pretty classic), the National Science Foundation also did a study that included a question about whether the Sun rotated around the Earth or the Earth around the Sun. And guess what happened. 1/4 Americans are apparently under the impression that the Sun orbits around the Earth. At first, this might make you laugh, it did for me at least, but the longer you think about it the more disturbing this is. For god’s sake, its the 21st century folks. Maybe Copernicus didn’t put the debate to bed, in truth his predictions for the orbits were actually less accurate than Geocentric models, because he thought the planets orbited in circles and not ellipses. But Galileo, and then Kepler, and then Newton, did put this to bed. And that was all before America was even a country. America, and the world, currently face a crisis with regards to climate change, caused by a scientifically illiterate populous and congress who have yet to heed the warnings of the scientific community as we are constantly warned of our unsustainable track. But maybe the problem is more basic. Global Climate Change is a lot harder to understand than gravity, at least the basics of both, maybe what Americans need is a focus on basic science education in order to deal with the larger problems of our society. At the very least, Obama should have a big announcement tomorrow that the Earth, and all the other planets, rotate around the Sun. Actually, maybe that wouldn’t help, that would probably lead to half of Americans thinking the Sun rotated around the Earth and their was just a big conspiracy to convince us otherwise. 

http://time.com/7809/1-in-4-americans-thinks-sun-orbits-earth/

Tonight we will all watch a lunar eclipse, which will last a while.  As we learn some of the basics of general relativity, maybe it is relevant to think about how it’s acceptance gradually came to be, since it’s conclusions are often counter-intuitive.

One of the most important tests of general relativity came in 1919, during a total solar eclipse.  Arthur Eddington traveled to the African Island of Principe to observe the eclipse.  Eddington was an astronomer, mathematician, internationalist, and pacifist.  Immediately after the great war, he was still willing to consider the new theories of a young German physicist, and he put them to the test during the 6 minutes and 51 seconds of total eclipse.  General relativity predicts a bending of light due to the curvature of space-time near a large mass.  The sun, while massive, is not very dense, and measuring the effect of the curvature of space-time near it’s surface requires extreme precision. Observations were made simultaneously in Brazil and West-Africa. Only during an eclipse is starlight visible next to the surface of the sun. They were monitoring a specific star, looking for a deviation from it’s expected position.  Dyson, Eddington and Davidson published their results the following year, and Einstein’s general relativity became the prevailing theory of gravity over the Newtonian, with headlines in newspapers around the world.

Famously, when asked by his assistant what his reaction would have been if general relativity had not been confirmed by Eddington and Dyson in 1919, Einstein replied: “Then I would feel sorry for the dear Lord. The theory is correct anyway.”

Rosenthal-Schneider, Ilse: Reality and Scientific Truth. Detroit: Wayne State University Press, 1980. p 74. See also Calaprice, Alice: The New Quotable Einstein. Princeton: Princeton University Press, 2005. p 227.)

Dyson, F.W.; Eddington, A.S.; Davidson, C.R. (1920). “A Determination of the Deflection of Light by the Sun’s Gravitational Field, from Observations Made at the Solar eclipse of May 29, 1919”. Phil. Trans. Roy. Soc. A 220 (571-581): 291–333. Bibcode:1920RSPTA.220..291D. doi:10.1098/rsta.1920.0009.

We are protected from the constant stream of charged particles coming from our sun by the magnetic field, which deflects them around the earth and directs some of the wind to the poles.  Our sun has a strong magnetic field generated by a strong dynamo of moving charges within it’s powerful convection cells.

Similarly, the liquid portion of Earth’s mantle churns and generates the field that protects our oceans, atmosphere, and life from the solar wind.  In the last post I discussed the atmosphere and water that Mars may have had in it’s past, and how the progressive freezing of it’s core contributed to the weakening of it’s magnetic field, and the subsequent stripping of it’s atmosphere.

The sun reverses polarity on an 11 year cycle.  Earth does the same, but with less regularity.  As you can see from the plot, we are overdue for one. As we look back at the basaltic rock record expanding from the mid ocean ridges, we can see from samples of magnetite that Earth’s polarity has reversed many times in our geologic history.  What would happen on earth during one of these reversals, when the field is weak and chaotic?  In class, freshman year, I naively asked if there would be aurora everywhere.  While this would be amazing, it is unlikely.  Rather, the scattered and multiplied poles would channel less of the total solar wind, and while they may exhibit their own aurora, it would be less intense than that which we observe now.  During the last brief reversal, the field is estimated to have had 5% of it’s current strength. It would be likely that one of these periods ranging from 200 to 10,000 years would be hard on life, but reversals do not correlate with extinctions in the fossil record, so it is likely that we would live through it.

This photo is from a computer simulation of earth’s convective liquid mantle. The polarity reversed at irregular intervals, and the behavior of earth’s field was actually well matched.

Vacquier, Victor (1972). Geomagnetism in marine geology (2nd ed.). Amsterdam: Elsevier Science. p. 38. ISBN 9780080870427.

Glatzmaier, Gary. “The Geodynamo”.

“Earth’s Inconstant Magnetic Field”. Retrieved 01-07-11.

Merrill, Ronald T.; McElhinny, Michael W.; McFadden, Phillip L. (1998). The magnetic field of the earth: paleomagnetism, the core, and the deep mantle. Academic Press. ISBN 978-0-12-491246-5.

The text was extremely vague on the processes of supermassive black holes. After a little more research, it is clear that this field remains very speculative,although there are some intriguing possibilities.

Image Source: Wikimedia Commons

The most prevalent theory states that supermassive black holes are the product of the collision of primordial black holes. These black holes formed shortly after the Big Bang due to the extremely high pressures. Two black holes and their accompanying galaxies then would have collided, forming some sort of binary system pulling in matter from the surrounding space. This amount of mass would exceed any sort of pressure limits and form one supermassive black hole. This theory is often preferred due to the fact that it explains the relative lack of intermediate-mass black holes. There are many stellar-mass black holes, which form as a result of core collapse. These are on the order of 3-15 solar masses. There are also a high amount of supermassive black holes, which begin around 100,000 solar masses and increase from there. The gap in between the two suggests very different formation patterns, and not a continuous spectrum of constantly added mass that was once imagined.

Image Source: Wikimedia Commons

Astrophysicists have been able to model the collision theory, which lends even more support. But other theoretical explanations abound. The theory of accretion is the most plausible, where a core collapse black hole occurs in a high density region and then forms accretion disks to increase the mass. This theory helps conserve angular momentum, as transfer to gas particles can keep the black hole from spinning too fast and evaporating. However, this does not explain the lack of intermediate-mass black holes. The Laser Interferometer Space Antenna that will hopefully launch in the next twenty years should gather enough data to answer the question of supermassive black hole formation.

Sources and Further Reading:

http://en.wikipedia.org/wiki/Supermassive_black_hole#Formation

http://www.universetoday.com/104044/how-do-black-holes-get-super-massive/

http://www.wired.com/2010/08/massive-black-hole-origin/

Mars is brilliantly visible right now as it rises in the eastern sky during each evening.  It is near closest approach to earth, and with a small telescope can be resolved to show the distinctive disk of a nearby planet, along with a red color that gives it a peculiarity in the night sky.

Our nearest neighbor has been well studied, enough so that some speculation has taken place on it’s past climate.  Some would perhaps like to imagine an earthlike ancient past with a thick atmosphere and liquid water oceans.  After a violent history of volcanism, the internal dynamo in the convective mantel of the planet slowed down progressively. Mars no longer has the necessary magnetic field strength to protect itself from solar wind in the way that Earth does, so it is known that its atmosphere may have been stripped of much of it’s density, and as a result Mars has lost it’s insulating properties.

The question becomes, how different was it during this time, say, on the order of 1GYA.

Some surface features can only be accounted for if we consider short periods of massive flooding, but new findings published in nature suggest that this ancient ocean world was the exception and not the rule.  Instead, most of Mars’s history was spent with conditions much colder than that of earth.  It never possessed the atmosphere to encourage runaway warming and greenhouse effect. Don’t let this dampen your imagination though, because there is much more to learn about the past of our cold and not-so-distant neighbor.

http://www.nature.com/news/ancient-mars-probably-too-cold-for-liquid-water-1.15042

Probably the oldest technique of an astronomer to measure the distance to the stars is trigonometric parallax. Parallax can be used to measure the distance to any object, and was first employed by travelers to measure the distance to mountain ranges, and estimate the heights of mountains. In the case of measuring the distance to a mountain, one measures the apparent angular position of the peak, walks some known distance perpendicular to the direction of the mountain forming the base of the triangle, then measures the angular position again. From the change in angular measurements and knowing how far they walked, simple trigonometry solves for the distance of the mountain.

Same is true for measuring distances to stars, except instead of walking a known distance, astronomers wait 6 months for the earth to move in position 2 AU, and then measure the second position of the star in the sky. The difference for measuring stellar distances however is that the triangles involved have extremely small angles. Beyond trigonometric parallax, astronomers can measure distances based off other techniques that involve analysis of the light from the star, but parallax by far is the most reliable. Thus, these other methods can be used in modern astrophysics to look further than parallax can measure precisely, but its crucial that these be calibrated with known distances measured by parallax.

Hubble uses a new technique called spatial scanning to improve its ability to measure arc seconds (1/3600th of a degree) so that it can now measure distances as far as 7,500 light years, rather than the 750 light years it was capable of before. They used this new capability to measure the distances to a class of stars called Cepheids that pulsate in brightness at a certain period. Because astronomers know the relationship between period and luminosity, the brightness can be calculated and the distance can be extrapolated from the flux of light reaching earth. Hubble’s new capability hopes to analyze our current accuracy with measuring distances with cepheids and type 1a supernova to get a more accurate map of the cosmos.

Sources:

http://www.sciencedaily.com/releases/2014/04/140411091943.htm

http://www.nasa.gov/press/2014/april/nasas-hubble-extends-stellar-tape-measure-10-times-farther-into-space/#.U0skruZdWr9

Modern Astrophysics 2nd edition by Caroll Ostlie