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    Venus comes to life at wavelengths invisible to human eyes

    nelda
    nelda

    Numero di messaggi : 524
    Età : 75
    Località : genova
    Data d'iscrizione : 03.07.08

    Venus comes to life at wavelengths invisible to human eyes Empty Venus comes to life at wavelengths invisible to human eyes

    Messaggio Da nelda il Gio 04 Dic 2008, 03:38

    Venus comes to life at wavelengths invisible to human eyes Titov_2008-04-03438_Figure_1_M
    Venus comes to life at wavelengths invisible to human eyes Spacer
    Venus in the ultraviolet

    Venus comes to life at wavelengths invisible to human eyes

    3 December 2008
    A
    pale yellow dot to the human eye, Earth’s twin planet comes to life in
    the ultraviolet and the infrared. New images taken by instruments on
    board ESA’s Venus Express provide insight into the turbulent atmosphere
    of our neighbouring planet.

    Using Venus Express, it is
    possible to compare what the planet looks like in different
    wavelengths, giving scientists a powerful tool to study the physical
    conditions and dynamics of the planet’s atmosphere.

    Venus comes to life at wavelengths invisible to human eyes Spacer Venus comes to life at wavelengths invisible to human eyes Titov_2008-04-03438_Figure_2b_S

    Venus in the ultraviolet and the infrared
    Observed
    in the ultraviolet, Venus shows numerous high-contrast features. The
    cause is the inhomogeneous distribution of a mysterious chemical in the
    atmosphere that absorbs ultraviolet light, creating the bright and dark
    zones.


    The ultraviolet reveals the structure of the clouds and the
    dynamical conditions in the atmosphere, whereas the infrared provides
    information on the temperature and altitude of the cloud tops.


    Venus comes to life at wavelengths invisible to human eyes Titov_2008-04-03438_Figure_3_S
    Venus comes to life at wavelengths invisible to human eyes Spacer
    Altimetry of the cloud tops

    With
    data from Venus Express, scientists have learnt that the equatorial
    areas on Venus that appear dark in ultraviolet light are regions of
    relatively high temperature, where intense convection brings up dark
    material from below. In contrast, the bright regions at mid-latitudes
    are areas where the temperature in the atmosphere decreases with depth.



    The temperature reaches a minimum at the cloud tops suppressing
    vertical mixing. This annulus of cold air, nicknamed the ‘cold collar’,
    appears as a bright band in the ultraviolet images.


    Observations in the infrared have been used to map the altitude of
    the cloud tops. Surprisingly, the clouds in both the dark tropics and
    the bright mid-latitudes are located at about the same height of about
    72 km.


    At 60° south, the cloud tops start to sink, reaching a minimum of about 64 km, and form a huge hurricane at the pole.


    Venus comes to life at wavelengths invisible to human eyes Titov_2008-04-03438_Composite_L

    Venus’s southern hemisphere

    In this mosaic, the infrared image is overlaid on an ultraviolet image,
    bringing the giant hurricane’s eye at the planet’s south pole to life.
    Its centre is displaced from the pole and the whole structure measures
    about 2000 km across, rotating around the pole in about 2.5 days.

    This study, carried out by D. Titov and colleagues has revealed that
    variable temperature and dynamical conditions at the Venus cloud tops
    are the cause of the global ultraviolet pattern.


    Venus comes to life at wavelengths invisible to human eyes Titov_2008-04-03438_Figure_5_L

    Venusian cloud top structure

    But the exact chemical species that creates the high-contrast zones still remains elusive, and the search is on.


    Notes for editors:

    These results appear in ‘Atmospheric structure and dynamics as the
    cause of ultraviolet markings in the clouds of Venus’ by D. Titov et
    al., published in the 4 December 2008 issue of the journal Nature.


    For more information:

    Dmitri Titov, Max Planck Institute for Solar System Research
    Germany
    Email: Titov @ mps.mpg.de


    Håkan Svedhem, ESA Venus Express Project Scientist
    Email: Hakan.Svedhem @ esa.int

      La data/ora di oggi è Sab 23 Nov 2019, 05:12