Now that the Moon is a waning crescent rising after midnight, observers in the British Isles can take advantage of at least three hours of darkness from 9pm BST to track down Comet Africano (C/2018 W2) at its closest and brightest as it speeds through the constellations of Pegasus, Pisces and Aquarius.
At 10:56 UT on 27 September, C/2018 W2 (Africano) passes just 0.494 astronomical units, or 74 million kilometres (46 million miles) from Earth. At this time the comet is moving against the stars of Pegasus at a rate of 3⅔ degrees per day, equivalent to the width of the full Moon every 3¼ hours.
Discovered almost simultaneously on 27 November 2018 by B. M. Africano with the Mount Lemmon 1.5-metre reflector and H. Groeller with the Catalina Sky Survey’s 0.68-metre Schmidt telescope (Africano’s report was submitted just 21 minutes earlier), C/2018 W2’s integrated magnitude is currently about +9 and may peak at about +8.5 over the coming week. Note that Comet Africano lies within a binocular field of view of outermost planet Neptune on the night of 3–4 October.
Having passed perihelion (closest point to the Sun) on 5 September, don’t miss any opportunities to view C/2018 W2 because it’s visiting the inner planets on a hyperbolic trajectory, meaning that it will never return to the Sun – unless its orbit is perturbed by the gravitational influence of a body in the outer Solar System in the distant future.
Have you ever seen planet Uranus? If UK skies are clear on the evening of Sunday, 22 November, the icy gas giant lies just 1.5 degrees (or three lunar diameters) from the 11-day-old waxing gibbous Moon, making it very easy to locate in binoculars and small telescopes. Here’s our online guide to locating this fascinating distant world.
Astronomers have discovered three planets orbiting an ultra-cool dwarf star just 40 light-years from Earth. These worlds have sizes and temperatures similar to those of Venus and Earth and are the best targets found so far for the search for life outside the solar system. They are the first planets ever discovered around such a tiny and dim star.
Three decades ago, on 25 August 1989, the Voyager 2 spacecraft raced past Neptune and its icy moon Triton, thrilling scientists and the public at large with spectacular images that remain unrivaled today.