Skytalk

Skytalk

By WHYYScienceNatural Sciences
Download on the App Store

Skytalk episodes

  • Falling Forward

    First, Dave Heller and Dr. Derrick Pitts discuss the Autumnal equinox, which is this Thursday at 10:21am.

    Next stops? Halloween, the time change on November 6th, and one of Dr. Pitts’ favorite days of the year, the Winter Solstice!

    Planet-gazers still have plenty to look at this week. Venus, Saturn, Mars early evening sky. Venus sinks within an hour after sunset. It’s also a good week to try to catch Mercury in the pre-dawn sky.

    Lots of interesting anniversaries this week:

    – Father of the American Apollo program Werner Von Braun arrived in the US on Sept. 20th in 1945. He was captured in Germany where he ran the V-2 rocket program, then brought to the US, where he established our rocket program.
    – The Russian robotic probe Luna 16 also landed on the moon on this date in 1970. It only stayed on the moon for 5 days – it returned lunar samples to earth at the end of the week.
    – Author H.G. Wells and Composer Gustave Holst share a birthday on Sept. 21 in 1866 and 1874, respectively.

    Image: Photographing London via Flickr

    5 min
  • Harvest Moon

    This Friday’s full moon is both the Harvest Moon and a penumbral eclipse. Penumbral means that the moon passes through the outer shadow of the earth, which is the weakest part of the Earth’s shadow. The effect is so slight that the eclipse can barely be seen. The Harvest Moon is the full moon closest to the Autumnal Equinox, which falls on September 22 this year.

    Mars and Saturn can be seen in the southwest night sky – with Venus rising out of the ever earlier September sunsets.

    Oleg Skripochka and Alexsey Ovchinin returned from the ISS last week along with the new American record-holder for time in space, Jeff Williams. Williams has spent 534 days off planet, more time in space than any other American. The next closest American astronaut is Peggy Whitsun who after her next flight will be at 531 days off planet. Amazingly, Williams is only 14th in the list of off-planeteers; Russian Gennady Padalka is in first place with 878 days off-planet.

    6 min
  • Don’t mistake this Dragonfly for a firefly
    Dragonfly 44, a galaxy 320 million light years away in the Coma Cluster, has a mass similar to our galaxy (a trillion times solar mass), but only 1/100th the number of stars. For the galaxy to hold together, it NEEDS the mass of the trillion-plus stars.
    Since the stars seen and gas detected don't add up to the mass needed for the galaxy's apparent stability, either it's being pulled apart by the Coma Cluster of galaxies or the galaxy is 99.99% dark matter - invisible matter that holds the galaxy together. Using a spectrograph on the Keck II telescope to clock the speed of one of the few stars visible, astronomers found a high enough speed to confirm the probable dark matter scenario. Not the first time - one found in Virgo earlier this year is just a bit less massive.
    This week's Franklin Institute Night Sky Observatory program may be our last chance to see Saturn and Mars together in the evening sky this year. Venus is low in the west just after sunset and Jupiter is gone for the season.
    A significant anniversary is coming up!  This Thursday marks the 50-year anniversary of Star Trek's premiere on TV (Thursday Sept. 8, 1966).
    13 min

About Skytalk

From the publisher's feed

A weekly discussion of what’s new and interesting in astronomy with Dr. Derrick Pitts