Terrestrial planet Structure Solar terrestrial planets Relative masses of the terrestrial planets of the Solar System, including the Moon During the formation of the Solar System, there were probably many more "terrestrial" planetesimals, but most merged with or were ejected by the four terrestrial planets. Density trends The uncompressed density of a terrestrial planet is the average density its materials would have at zero pressure. The densities of the solar terrestrial planets, the Moon, and the three largest asteroids are shown below. The main exception to this rule is the density of the Moon, which probably owes its lesser density to its unusual origin. It is unknown whether extrasolar terrestrial planets in general will also follow this trend. Extrasolar terrestrial planets During the early 1990s, the first extrasolar planets were discovered orbiting the pulsar PSR B1257+12, with masses of 0.02, 4.3, and 3.9 times that of Earth's, by pulsar timing. Frequency Types
Sex Chromosome Specialization and Degeneration in Mammals To view the full text, please login as a subscribed user or purchase a subscription. Click here to view the full text on ScienceDirect. Sex chromosomes—particularly the human Y—have been a source of fascination for decades because of their unique transmission patterns and their peculiar cytology. Register an Account If you do not have an account, create one by clicking the button below, and take full advantage of this site's features.
CH star CH stars are particular type of carbon stars which are characterized by the presence of exceedingly strong CH absorption bands in their spectra. They belong to the star population II, meaning they're metal poor and generally pretty middle-aged stars, and are underluminous compared to the classical C–N carbon stars. Many CH stars are known to be binaries, and it's reasonable to believe this is the case for all CH stars. Like Barium stars, they are probably the result of a mass transfer from a former classical carbon star, now a white dwarf, to the current CH-classed star. Organic farming is rarely enough Organic farming is sometimes touted as a way to feed the world's burgeoning population without destroying the environment. But the evidence for that has been hotly debated. Now, a comprehensive analysis of the existing science, published in Nature1, suggests that farming without the use of chemical fertilizers and pesticides could supply needs in some circumstances. maxim.photoshelter.com/Alamy Strawberries are among the few crops that grow almost as well on organic farms as in conventional agriculture. “I think organic farming does have a role to play because under some conditions it does perform pretty well,” says Verena Seufert, an Earth system scientist at McGill University in Montreal, Canada, and the study’s lead author. Area under inspection Seufert's meta-analysis reviewed 66 studies comparing the yields of 34 different crop species in organic and conventional farming systems. Fruitful farming “This is where yield increases are most needed,” says Seufert.
Astrochemistry Astrochemistry is the study of the abundance and reactions of chemical elements and molecules in the universe, and their interaction with radiation. The discipline is an overlap of astronomy and chemistry. The word "astrochemistry" may be applied to both the Solar System and the interstellar medium. The study of the abundance of elements and isotope ratios in Solar System objects, such as meteorites, is also called cosmochemistry, while the study of interstellar atoms and molecules and their interaction with radiation is sometimes called molecular astrophysics. The formation, atomic and chemical composition, evolution and fate of molecular gas clouds is of special interest, because it is from these clouds that solar systems form. Spectroscopy One particularly important experimental tool in astrochemistry is spectroscopy, the use of telescopes to measure the absorption and emission of light from molecules and atoms in various environments. Research
10 of the World's Deadliest Plants — And How They Kill You The predator must also, for some reason or another, want to continue to pursue this plant for the toxicity to go so high. Additionally, why this particular poison for that plant? Evolution, fascinating, indeed. I do wonder if any of these are actually the predator. Maybe, the prey provide something that helps promulgates their genes. A lot of plant toxins are geared towards insects. (If you're a plant trying to fend off a moose, poison doesn't do you as much good, because the moose is so big that by the time your poison kills it, the moose has already destroyed you and 15-20 minutes worth of your neighbors. Since insects and mammals share a common (nerve- and muscle-endowed) evolutionary ancestor, there's a fair number of chemicals that can disrupt systems in both groups.
Primary Life Support System A Portable Life Support System from the Apollo A7L suit, with its outer cover removed A Primary (or Portable or Personal) Life Support System (or /Subsystem) (PLSS), is a device connected to an astronaut or cosmonaut's spacesuit, which allows extra-vehicular activity with maximum freedom, independent of a spacecraft's life support system. The PLSS is generally worn like a backpack. The functions performed by the PLSS include: regulating suit pressureproviding breathable oxygenremoving carbon dioxide, humidity, odors, and contaminants from breathing oxygencooling and recirculating oxygen through the pressure garment, and water through a Liquid Cooling and Ventilation Garment or Liquid Cooling Garment.two-way voice communicationdisplay and/or telemetry of suit health parameterstelemetry of an indicator of the wearer's immediate health (e.g. heart rate) Apollo PLSS The interior of the Apollo PLSS. The PLSS was 26 inches (66 cm) high, 18 inches (46 cm) wide, and 10 inches (25 cm) deep.
5 Fragrant Plants for a Small Space When I visit my mom she puts me to work 'dead-heading' her lavender. As I trim away the dead blossoms the smell of lavender surrounds me and attracts quite a few bees. It reminds me how important scent is in a garden and what an integral experience it is to losing yourself in the outdoors. In a small space like a balcony or small deck, using plants that give off a scent can make the experience that much richer. Here are 5 of my favorite fragrant plants perfect for a small space… 1. Lavender: There are hundreds of varieties of Lavender but we normally go for whatever the nursery has available and what smells the best. 2. 3. 4. 5. Of course there are roses and freesias and jasmine and basil and rosemary, the list goes on and on with plants that have amazing scents.
ILC Dover EMU suit worn during EVA on the International Space Station ILC Dover, LP (also known as ILC) is an American special engineering development and manufacturing company based in Frederica, Delaware. ILC specializes in the use of high-performance flexible materials, serving the aerospace, personal protection, and pharmaceutical industries. Best known for making space suits for NASA, ILC outfitted every United States astronaut in the Apollo program, including the twelve that walked on the moon. Other ILC products include the airbag landing devices for Mars Pathfinder and Mars Exploration Rover (MER) missions; lighter-than-air vehicles, including airships, aerostats, and zeppelins; chemical, biological, radiological, and nuclear (CBRN) masks and hood systems; and flexible powder-containment solutions for the pharmaceutical industry. History M40 Gas Mask In 1974, the Skylab program ended, and ILC faced an immediate need to diversify their product offerings. Space suits Shuttle
Fuzzball (string theory) Theorized fuzzballs, like classic black holes, distort spacetime and bend light. Here, the edge of the central dark spot, the event horizon, delineates not only the threshold where its escape velocity equals the speed of light but also a fuzzball’s physical surface. (Artist rendition) Fuzzballs are theorized by some superstring theory scientists to be the true quantum description of black holes. The information paradox wherein the quantum information bound in in‑falling matter and energy entirely disappears into a singularity; that is, the black hole would undergo zero physical change in its composition regardless of the nature of what fell into it.The singularity at the heart of the black hole, where conventional black hole theory says there is infinite spacetime curvature due to an infinitely intense gravitational field from a region of zero volume. Fuzzballs become less dense as their mass increases due to fractional tension.
Astronomical object Above the round domes of La Silla Observatory, three astronomical objects in the Solar System — Jupiter (top), Venus (lower left), and Mercury (lower right). Types of Solar System bodies. Astronomical objects or celestial objects are naturally occurring physical entities, associations or structures that current science has demonstrated to exist in the observable universe. The term astronomical object is sometimes used interchangeably with astronomical body. The constituents of a galaxy are formed out of gaseous matter that assembles through gravitational self-attraction in a hierarchical manner. The various distinctive types of stars are shown by the Hertzsprung–Russell diagram (H–R diagram)—a plot of absolute stellar luminosity versus surface temperature. Categories by location The table below lists the general categories of objects by their location or structure. See also References Jump up ^ "Three Planets Dance Over La Silla". External links
Interstellar nitrogen monohydride Nitrogen monohydride (NH) is a simple compound that has been detected in interstellar space. History One of the earliest papers on the NH molecule was in 1976 by Richard M. Crutcher and William D. Interstellar NH was discovered in outer space for the first time in 1991 by D. Shortly after NH’s discovery, Wagenblast, R. At the end of their research, they concluded that even though the gas-phase formation of NH is given a large rate coefficient, NH was calculated to be underabundant with respect to the observations by a factor of 30. Chemistry Within diffuse clouds H- + N → NH + e- is a major formation mechanism. NH is destroyed in diffuse clouds by photodissociation and photionization. Significance See also Imidogen References