UK observers with a clear sky an hour before sunrise on Friday 28 October should look very low in the east-southeast to see the slim crescent of the 27-day-old Moon just 1.8 degrees from largest planet Jupiter. In this simulated 10×50 binocular view, note that the Moon and Jupiter are joined by third-magnitude star gamma (γ) Virginis, commonly known as Porrima. This is a beautiful 2.5-arcsecond double star in medium-sized backyard telescopes when it is higher in the sky and seeing conditions are good. AN graphic by Ade Ashford.It’s time to celebrate the return of the king — the king of the planets, that is. Jupiter was in conjunction with the Sun on 26 September, but the solar system’s largest planet is now creeping back into the pre-dawn sky against the stellar backdrop of the constellation Virgo where it can be seen from the UK very low in the east-southeast about an hour before sunrise.
The configuration of Jupiter’s four Galilean moons Io, Europa, Ganymede and Callisto in the UK dawn twilight of Friday 28 October 2016 as seen with an erect-image telescope (north is up and east to the left). AN graphic by Ade Ashford.An added incentive to get up early to view Jupiter occurs on Friday 28 October when the slim crescent of a 27-day-old Moon lies just 1.8 degrees from the magnitude -1.7 planet as seen from the British Isles. The pair will look magnificent in binoculars where you might glimpse another object — third-magnitude star gamma (γ) Virginis, otherwise known as Porrima.
For telescope owners, Porrima holds another treat in store — though one that will be appreciated in the spring when the star lies higher in the sky and seeing conditions will be much improved. Gamma Virginis is a glorious double star with virtually identical components separated by just 2.5 arcseconds, hence a 4-inch (10-cm) aperture telescope employing a magnification of around 200x is required. Porrima is a true binary with a period of about 169 years and lies some 38 light-years from Earth.
Inside the magazine
For a comprehensive guide to observing all that is happening in the current month’s sky, tailored to Western Europe, North America and Australasia, obtain a copy of the October 2016 edition of Astronomy Now.
Scientists using the NASA/ESA Hubble Space Telescope have produced new maps of Jupiter that show the continuing changes in its famous Great Red Spot. The images also reveal a rare wave structure in the planet’s atmosphere that has not been seen for decades. This is the first in a series of annual portraits of the solar system’s outer planets which will help researchers study how they change over time.
The Earth’s magnetic field is produced by the geodynamo, the rapid motion of huge quantities of liquid iron alloy in the Earth’s outer core. A team of French researchers suggests that elastic deformation of our planet’s mantle due to tidal effects caused by the Moon — overlooked until now — transfers energy to the Earth’s outer core, keeping the geodynamo active.
Juno programme officials hold a news conference at NASA’s Jet Propulsion Laboratory following the successful orbital insertion of the space probe around the gas giant Jupiter.
