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Archive for February, 2014

Brightest Lunar Explosion Ever Seen

On 2013 September 11 at 20h07m28.s68 ± 0.s01 UTC, two telescopes operated in the framework of our lunar impact flashes monitoring project recorded an extraordinary flash produced by the impact on the Moon of a large meteoroid at selenographic coordinates 17 ?.2 ± 0 ?.2 S, 20 ?.5 ± 0 ?.2 W. The peak brightness of this flash reached 2.9 ± 0.2 mag in V and it lasted over 8 s. The estimated energy released during the impact of the meteoroid was 15.6 ± 2.5 tons of TNT under the assumption of a luminous efficiency of 0.002. This event, which is the longest and brightest confirmed impact flash recorded on the Moon thus far, is analysed here. The likely origin of the impactor is discussed. Considerations in relation to the impact flux on Earth are also made.

Monthly Notices of the Royal Astronomical Society, 2014.

record-breaking meteorite strike on the moon

The impact of a large meteorite on the lunar surface on Sept. 11, 2013, resulted in a bright flash, observed by scientists at the MIDAS observatory in Spain.
Credit: J. Madiedo / MIDAS

On Sept. 11, 2013, a pair of telescopes from a project called MIDAS (Moon Impacts Detection and Analysis System) monitored the blast from a meteoroid crashing into the lunar surface. The meteorite hit at a speed of 37,900 mph (61,000 km/h), gouging out a new crater roughly 131 feet (40 meters) wide in an ancient lava-filled lunar basin known as Mare Nubium. The energy released by the impact was comparable to an explosion of roughly 15 tons of TNT, and was at least three times more powerful than the largest previously observed event. The flash, which lasted for about 8 seconds, was about as bright as Polaris, the North Star. The high-speed collision was recorded on video and would have been clearly visible to anyone on Earth who happened to look at the moon at the right time.

The uncertainty of the impact is fairly high, the team who made the discovery said in their paper, and the team cautioned that specifics about the meteorite’s impact were difficult to nail down, in part because its origin cannot be determined. “Two sources have been considered for the impactor,” they write. “The event was compatible with the impact geometry of the September Epsilon Perseids minor shower, but it could also be associated with a sporadic meteorid.” If it was part of the September Epsilon Perseids meteor shower, it would have a very high velocity relative to the moon, and wouldn’t need as much mass to cause an impact with this energy. In this case, the rock would have been about 45kg and 36cm across. If, however, it was a sporadic meteoroid, the velocity would be lower and the mass greater, perhaps a mass of 450kg, and a diameter as large as 1.4 meters.

The MIDAS project has been running since 2009, and has an automated pipeline for identifying impacts. The statistics it has generated suggest that some early estimates of the rate at which Earth is bombarded may be low by as much as a factor of 10. In their paper, the team noted “Thus, the impact energy of the lunar impact flash would be equivalent to an impact energy of 28.3 ± 4.5 tons of TNT on Earth for the sporadic meteoroid and 24.3 ± 3.8 tons of TNT for the SPE meteoroid. So, by performing the corresponding surface area scaling between both bodies, the impact rate on Earth for events with an energy above these values would be of about 1680 ± 1050 events per year.”

“Our telescopes will continue observing the Moon as our meteor cameras monitor the Earth’s atmosphere,” said Madiedo and Ortiz in a press release. “In this way we expect to identify clusters of rocks that could give rise to common impact events on both planetary bodies. We also want to find out where the impacting bodies come from.”

A video of the impact has been posted on YouTube.

Close Encounters Of The Sexual Kind

A good bit of imagination has gone into attempts to represent close encounters of a sexual kind. Major authors, such as Ursula K. Le Guin, Philip Jose Farmer, and Octavia Butler, have written critically-acclaimed novels in which deep emotional, intimate, and sexual relations between humans and aliens form the central narrative. Significant episodes of the various Star Trek series have also shown intimate relations among aliens — sometimes between humans and aliens, sometimes among different alien species (such as the relationship between the Klingon Whorf and the Trill Jadzia Dax in Deep Space Nine). Star Trek’s own Mr. Spock was the product of a marriage between a human female and a male alien from the fictional planet Vulcan.

The human/alien sex trope typically assumes that an alien species would reproduce in a manner that’s compatible with how humans reproduce, but that can be a dangerous assumption, judging by the way many species on earth reproduce. The male of the deep sea anglerfish, for example, attaches to the female permanently, fusing with her blood stream and gradually atrophying until they are just a pair of gonads that release sperm into the female in response to hormonal cues in her blood, a process known as sexual parasitism. Other species, such as the New Mexico whiptail, are an all-female species. Adult female New Mexico whiptails reproduce solely through parthenogenesis (a type of asexual reproduction in which a female gamete or egg cell develops into an individual without fertilization), laying unfertilized eggs that develop into other female whiptails.

There are organisms without distinctive male and female forms. The black mold Rhizopus nigricans, displays an unusual form of reproduction known as “heterothallism.” This species of fungus requires two organisms are for fertilization and replication to take place. However, the two sexes are physically indistinguishable. There are no constant differences between members of opposite mating groups other than their reciprocal behavior when crossed. Thus, it is impossible to designate one form of the black mold as male and the other as female. Customarily the complementary groups are labeled merely “+” and “-” for convenience during experiments.

If some species have no distinctive examples of male and female forms, others have more than two sexes. Some species have one female and two male genders include red deer who have two male morphs (distinct forms of an organism or species), one with antlers and one without, known as hummels or notts, as well as several species of fish such as plainfin midshipman fish and coho salmon. Others have one female and three male genders, including bluegills, where four distinct size and color classes exhibit different social and reproductive behaviors, the spotted European wrasse (Symphodus ocellatus), the Oreochromis mossambicus cichlid, and the ornate tree lizard (Urosaurus ornatus).1 Slime mold has thirteen sexes, while the fungus Schizophyllum commune has over 28,000 sexes.

Other organisms lack specific maleness and femaleness, but exhibit an alternating or intermediate condition. For example, simultaneous hermaphrodites possess at once both female and male sex organs. Ovaries and testes are present together in the same individual. Matings occur in pairs, with each partner serving both sexual roles at the same time. Planarians, earthworms, sponges and snails fall into this category, as well as a few among more highly evolved vertebrates are known, such as the belted flamefish (Serranus subltgarius). Some simultaneous hermaphrodites form harems, in which a single male supervises a school of females. If the male is killed, the dominant female in the harem transitions and takes his place. In such harems, the male is usually responsible for defending the school from invaders and protecting his territory to ensure that his flock does not wander astray or encounter potential dangers.

There are also species where individuals start life as one sex and finish it as another, called sequential hermaphrodites. There are two types of sequential hermaphrodites. Animals which are born male with the ability to become female exhibit a trait of protandry. Protogyny, on the other hand, is a trait in which animals are born as females, with the ability to become males later in life. Depending on the species, simultaneous hermaphrodites may change sex only once, or they may be able to flip back and forth between genders several times. Oysters, for example, are born as males, then spend the rest of their lives switching back and forth between male and female in irregular cycles a few months long.

Given these tremendous potential biological differences, would or could copulation be possible at all between humans and extraterrestrials?

Maybe.

There are well-documented cases of attempted and successful sex between different species. These include dolphins and humans. seals and penguins, otters and seals, sheep and deer, orangutans and humans, and humans with various farm animals. This suggests that, if humans were to mingle socially with alien races, interspecies sexual contacts are at least possible.

Even if such activity were possible, how likely would it be? Could humankind and an alien race derive sexual pleasure from mutual physical encounters?

Suppose, for example, we discovered an alien race that is sequential hermaphroditic. In this society, individuals spend their early life neither male or female, then attain puberty and enter their first sexually active phase as functioning males. After a certain amount of time, latent ovaries within them ripen into maturity, and the individual, now considered an adult, spends the remainder of its life as a female.

In such a society, monogamous marriage as we know it would be impossible. Husbands would change into wives, and males would be too immature psychologically to be treated as anything other than young lovers. Since all fertile middle-aged females in a family in theory could mate with any or all male children, it’s likely there would be complex incest prohibitions. To offset the negative effects of inbreeding, exchanges of matriarchs would occur between families. Love as humans understand it probably would not exist. In such a society, females would likely have strong affective and familial non-sexual ties with other females. Human concepts of male/female romantic relationships would be quite incomprehensible to them. Even if their sexual organs were compatible with those of a human, and neither species found the physical appearance of the other repellant, the sensitivities of the alien race would likely be such that there wouldn’t be any desire on their part to have any type of sexual contact with humans.

Footnotes

1. See Roughgarden, Joan (2004). Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People. University of California Press. ISBN 0-520-24073-1 Especially chapter 6, Multiple Gender Families, pp. 75–105.

Further Reading

The Sex Is Out of This World: Essays on the Carnal Side of Science Fiction, edited by Sherry Ginn, Michael G. Cornelius, Donald E. Palumbo, and C.W. Sullivan III

Alien Sex: From Ming the Merciless to “The Lovers, David Lumb and Jonathan Alexander, Los Angeles Review of Books

Alien Sex Acts in Feminist Science Fiction: Heuristic Models for Thinking a Feminist Future of Desire“. Alcena Madeline Davis Rogan, PMLA, Vol. 119, No. 3, Special Topic: Science Fiction and Literary Studies: The Next Millennium (May, 2004), pp. 442-456

NASA’s Crowdsourced Search for Planetary Habitats

NASA Goddard announced on January 30th that it’s sponsoring a new project and website, Disk Detective, which allows people to discover “embryonic planetary systems” hidden in the data generated by NASA’s Wide-field infrared Survey Explorer (WISE) mission. The data mining and analysis effort is NASA’s largest ever crowdsourcing project, and the agency says its main goal is to produce publishable scientific results.

“Through Disk Detective, volunteers will help the astronomical community discover new planetary nurseries that will become future targets for NASA’s Hubble Space Telescope and its successor, the James Webb Space Telescope,” said James Garvin, the chief scientist for NASA Goddard’s Sciences and Exploration Directorate.

WISE was designed to survey the entire sky at infrared wavelengths. From a perch in Earth orbit, the spacecraft completed two scans of the entire sky between 2010 and 2011. It took detailed measurements on more than 745 million objects, representing the most comprehensive survey of the sky at mid-infrared wavelengths currently available.

WISE was shut down in 2011 after its primary mission was completed, but was reactivated in September 2013, renamed the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE), and given a new mission, to assist NASA’s efforts to identify the population of potentially hazardous near-Earth objects (NEOs). NEOWISE also can assist in characterizing previously detected asteroids that could be considered potential targets for future exploration missions.

Developed alongside Zooniverse, a network of scientists, software developers, and educators, the project will make sifting through the astronomical data easier. From 2010 to 2011 WISE, which is locked in Earth orbit, scanned the entire sky in infrared, measuring some 745 million objects in detail. NASA is in the process of searching through this data for planets that form and grow in “dust-rich circumstellar disks,” which shine brightly in infrared wavelengths.

The problem is that other objects, such as galaxies, interstellar dust clouds, and asteroids, also shine in infrared. This infrared noise makes it difficult to identify planet-forming environments – Young Stellar Object disks (gaseous and less than 5 million years old), and debris disks, which are 5 million years or older and contain little to no gas. The former are found in or near young star clusters, while the latter contains “belts of rocky or icy debris that resemble the asteroid and Kuiper belts” found in our solar system.

To deal with this problem, Disk Detective takes images from WISE and other sky surveys (the James Webb Telescope will contribute data in the future) and converts them to brief animations the website calls flip books. Volunteers then classify objects according to specific but simplecriteria, such as whether the image is round or includes multiple objects. Working on this cataloged image analysis, astronomers will then decide which objects deserve greater attention.

Herbig-Haro 30

Herbig-Haro 30 is the prototype of a gas-rich young stellar object disk. The dark disk spans 40 billion miles in this image, cutting the bright nebula in two and blocking the central star from direct view. Volunteers can help astronomers find more disks like this through DiskDetective.org [Credit: NASA/ESA/C. Burrows (STScI)]

For more information, you can watch the NASA | Disk Detective: Search for Planetary Habitats video, and this Hubble Space Telescope Google hangout.