In the small hours of Friday, 16 October, innermost planet Mercury reaches its greatest westerly elongation from the Sun. For those of you in the UK with a flat, unobscured eastern horizon and willing to get up an hour before sunrise, the next few days provide your best opportunity to see Mercury from the Northern Hemisphere during 2015.
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.
Now that planet Saturn is effectively lost in the dusk twilight for UK-based observers, you may be wondering what has happened to the other four bright naked-eye planets. Far from disappearing, they have just transferred to the morning sky. From 8—11 October, the waning crescent Moon acts as a guide to Venus, Mars, Jupiter then Mercury in the eastern dawn sky.
Jupiter’s moon Io is the most volcanically active world in the solar system, with hundreds of volcanoes, some erupting lava fountains up to 250 miles high. New NASA research suggests that tides flowing in a subsurface ocean of molten rock, or magma, could explain why Io’s volcanoes appear in the “wrong” place compared to models that predict how the moon’s interior is heated.
Researchers at Southwest Research Institute (SwRI) and Queen’s University in Canada have unravelled the mystery of how Jupiter and Saturn likely formed using computer simulations. The discovery, which changes our view of how all planets might have formed, also suggests that the gas giants in the solar system probably formed before the terrestrial planets.
The Gemini Planet Imager instrument has discovered and photographed its first planet. Dubbed 51 Eridani b, the body is a methane-enshrouded gas giant that is the most Jupiter-like exoplanet ever directly imaged, in a planetary system just 20 million years old. It may hold the key to understanding how large planets form in the swirling accretion discs around stars.
An international team of scientists has solved an age-old scientific riddle by discovering that planetary rings, such as those orbiting Saturn, have a universally similar particle distribution. The study also suggests that Saturn’s rings are essentially in a steady state that does not depend on their history.
Planet Venus — the brilliant lantern hanging over the west-northwest horizon at dusk — reaches its greatest elongation from the Sun on June 6th. It’s still a month away from reaching peak brightness, but before then it has a spectacular close conjunction with largest planet Jupiter at the end of June.