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The Equator
The Earth is wearing a belt is an age-old visual device teachers have used to explain the equator. In this volume, young readers will expand their comprehension of this important concept. With an understanding of the equator comes a grasping of the rotation of the Earth, climate, weather, and many other age-appropriate science concepts. Clean, accessible art on every spread including diagrams, maps, and full-color photographs help readers grasp these curriculum topics. That important main line of latitude we call the equator is made familiar through clean text and graphics in a way that every elementary reader is sure to understand!
Book
Asteroseismic detection of latitudinal differential rotation in 13 Sun-like stars
The Sun rotates faster at its equator than at its poles. This process is known as differential rotation and is seen in the motion of sunspots. Helioseismology has shown that the effect extends into the Sun's interior. It has not been possible to measure whether other stars also experience equivalent differential rotation. Benomar et al. used the Kepler spacecraft to monitor stellar oscillations of a group of Sun-like stars. By decomposing the oscillations into separate frequencies, they searched for signs of differential rotation. Several stars do indeed seem to have equators that spin faster than their poles, and none indicated the opposite pattern. Science , this issue p. 1231 Stellar oscillations show that some solar-type stars spin faster at their equators than their poles. The differentially rotating outer layers of stars are thought to play a role in driving their magnetic activity, but the underlying mechanisms that generate and sustain differential rotation are poorly understood. We report the measurement using asteroseismology of latitudinal differential rotation in the convection zones of 40 Sun-like stars. For the most significant detections, the stars’ equators rotate approximately twice as fast as their midlatitudes. The latitudinal shear inferred from asteroseismology is much larger than predictions from numerical simulations.
Journal Article
Earth's hemispheres
The division of the Earth into hemispheres isn t the easiest concept to teach or grasp. It involves geography, spatial awareness, map-reading abilities, and more. This volume makes it easy for any reader to develop a solid comprehension of this critical social studies lesson! Vivid, full-color maps and photographs are integrated with accessible main text to aid young readers understanding of this sometimes-tough topic. This essential book is a useful and valuable addition to any library s collection!
Book
Challenges to Equatorial Plasma Bubble and Ionospheric Scintillation Short-Term Forecasting and Future Aspects in East and Southeast Asia
Equatorial plasma bubbles (EPBs) can cause rapid fluctuations in amplitude and phase of radio signals traversing the ionosphere and in turn produce serious ionospheric scintillations and disrupt satellite-based communication links. Whereas numerous studies on the generation and evolution of EPBs have been performed, the prediction of EPB and ionospheric scintillation occurrences still remains unresolved. The generalized Rayleigh–Taylor (R–T) instability has been widely accepted as the physical mechanism responsible for the generation of EPBs. But how the factors, which seed the development of R–T instability and control the dynamics of EPBs and resultant ionospheric scintillations, change on a short-term basis are not clear. In the East and Southeast Asia, there exist significant differences in the generation rates of EPBs at closely located stations, for example, Kototabang (0.2°S, 100.3°E) and Sanya (18.3°N, 109.6°E), indicating that the decorrelation distance of EPB generation is small (hundreds of kilometers) in longitude. In contrast, after the initial generation of EPBs at one longitude, they can drift zonally more than 2000 km and extend from the magnetic equator to middle latitudes of 40° or higher under some conditions. These features make it difficult to identify the possible seeding sources for the EPBs and to accurately predict their occurrence, especially when the onset locations of EPBs are far outside the observation sector. This paper presents a review on the current knowledge of EPBs and ionospheric scintillations in the East and Southeast Asia, including their generation mechanism and occurrence morphology, and discusses some unresolved issues related to their short-term forecasting, including (1) what factors control the generation of EPBs, its day-to-day variability and storm-time behavior, (2) what factors control the evolution and lifetime of EPBs, and (3) how to accurately determine ionospheric scintillation from EPB measurements. Special focus is given to the whole process of the EPB generation, development and disruption. The current observing capabilities, future new facilities and campaign observations in the East and Southeast Asia in helping to better understand the short-term variability of EPBs and ionospheric scintillations are outlined.
Journal Article
Regulation of ionospheric plasma velocities by thermospheric winds
Earth’s equatorial ionosphere exhibits substantial and unpredictable day-to-day variations in density and morphology. This presents challenges in preparing for adverse impacts on geopositioning systems and radio communications even 24 hours in advance. The variability is now theoretically understood as a manifestation of thermospheric weather, where winds in the upper atmosphere respond strongly to a spectrum of atmospheric waves that propagate into space from the lower and middle atmosphere. First-principles simulations predict related, large changes in the ionosphere, primarily through modification of wind-driven electromotive forces: the wind-driven dynamo. Here we show the first direct evidence of the action of a wind dynamo in space, using the coordinated, space-based observations of winds and plasma motion made by the National Aeronautics and Space Administration Ionospheric Connection Explorer. A clear relationship is found between vertical plasma velocities measured at the magnetic equator near 600 km and the thermospheric winds much farther below. Significant correlations are found between the plasma and wind velocities during several successive precession cycles of the Ionospheric Connection Explorer’s orbit. Prediction of thermospheric winds in the 100–150 km altitude range emerges as the key to improved prediction of Earth’s plasma environment.
Observations from the National Aeronautics and Space Administration Ionospheric Connection Explorer confirm the link between thermospheric winds and ionospheric plasma variability.
Journal Article
The Data Release of the Sloan Digital Sky Survey-II Supernova Survey
This paper describes the data release of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey conducted between 2005 and 2007. Light curves, spectra, classifications, and ancillary data are presented for 10,258 variable and transient sources discovered through repeat ugriz imaging of SDSS Stripe 82, a 300 deg2 area along the celestial equator. This data release is comprised of all transient sources brighter than r 22.5 mag with no history of variability prior to 2004. Dedicated spectroscopic observations were performed on a subset of 889 transients, as well as spectra for thousands of transient host galaxies using the SDSS-III BOSS spectrographs. Photometric classifications are provided for the candidates with good multi-color light curves that were not observed spectroscopically, using host galaxy redshift information when available. From these observations, 4607 transients are either spectroscopically confirmed, or likely to be, supernovae, making this the largest sample of supernova candidates ever compiled. We present a new method for SN host-galaxy identification and derive host-galaxy properties including stellar masses, star formation rates, and the average stellar population ages from our SDSS multi-band photometry. We derive SALT2 distance moduli for a total of 1364 SN Ia with spectroscopic redshifts as well as photometric redshifts for a further 624 purely photometric SN Ia candidates. Using the spectroscopically confirmed subset of the three-year SDSS-II SN Ia sample and assuming a flat ΛCDM cosmology, we determine M = 0.315 0.093 (statistical error only) and detect a non-zero cosmological constant at 5.7 .
Journal Article
Statistical Survey of Fast Magnetosonic Waves in the L < 2 Region
Fast magnetosonic waves are electromagnetic waves with frequencies ranging from a few Hertz to several hundred Hertz, observed primarily near the magnetic equator. Recent studies demonstrate that magnetosonic waves can propagate into the L<2 $L< 2$ region, while their distributions and propagation properties there remain unclear. Using data from Van Allen Probes, we present the first systematic survey of magnetosonic waves' spatial distribution in the L<2 $L< 2$ region, revealing important characteristics of their propagation and evolution. The frequency spectra of magnetic power spectral densities reveal that under disturbed geomagnetic conditions, the bandwidth of fast magnetosonic waves shifts to higher frequencies, and the spectra exhibit a radial inner boundary and a low‐frequency boundary, both of which depend on geomagnetic conditions. These findings advance our understanding of the propagation and evolution of magnetosonic waves in the L<2 $L< 2$ region and their potential role in the inner magnetosphere.
Journal Article
Global warming is causing a more pronounced dip in marine species richness around the equator
The latitudinal gradient in species richness, with more species in the tropics and richness declining with latitude, is widely known and has been assumed to be stable over recent centuries. We analyzed data on 48,661 marine animal species since 1955, accounting for sampling variation, to assess whether the global latitudinal gradient in species richness is being impacted by climate change.We confirm recent studies that show a slight dip in species richness at the equator. Moreover, richness across latitudinal bands was sensitive to temperature, reaching a plateau or declining above a mean annual sea surface temperature of 20 °C for most taxa. In response, since the 1970s, species richness has declined at the equator relative to an increase at midlatitudes and has shifted north in the northern hemisphere, particularly among pelagic species. This pattern is consistent with the hypothesis that climate change is impacting the latitudinal gradient in marine biodiversity at a global scale. The intensification of the dip in species richness at the equator, especially for pelagic species, suggests that it is already too warm there for some species to survive.
Journal Article
Utilization of MASH Planetary Nebula Catalogue of the Year 2006 for the Determination of the Milky-Way Plane
In this paper, the equatorial coordinates of the galactic pole (αp, δp) for the epoch 2000.0 was computed using the most recent data of the MASH planetary nebulae catalogue of the year 2006. As a result, the inclination of the Milky way plane to the celestial equator i^sub g^ and the right ascension of its ascending node Ω^sub g^ at the same epoch are also computed.
Journal Article