Go to Sai Kung’s Astropark to view a wondrous sight; asteroid Vesta will be shining beautifully

29 April 2025 rmedcalf SCIENCE 0

_{Photo: NASA}

The asteroid Vesta, one of the largest in the asteroid belt, will be in opposition on 2 May and will be at its brightest. You will be able to see it with the naked eye if you can view in a dark sky (no light pollution). Being in opposition means the Earth is between the Sun and the asteroid. Vesta is named after the virgin goddess of the home. Vesta is travelling at about 19.3 km a second, whizzing around the Sun once every 3.6 years. The asteroid is 525 km in diameter. If you managed to land on it , you had better wrap up because the temperature may be as low as -198 celsius.

In size Vesta is thought to be second only to the minor planet Ceres. It makes up an estimated 9 per cent of the asteroid belt. Vesta has two enormous craters where fragments were blasted off because of collisions. Debris from these events fell to Earth as meteorites so scientists know a lot about the composition of Vesta. She is the brightest asteroid visible from Earth, because her light-coloured surface reflects the Sun’s rays well.

_{NASA’s Dawn spacecraft circling asteroid Vesta Image: NASA}

NASA’s Dawn spacecraft entered orbit with Vesta on 16 July 2011 and spent one year flying around the asteroid, leaving on 5 September 2012 en-route to its next destination the proto-planet Ceres.

Vesta orbits the Sun between Mars and Jupiter within the asteroid belt. Her rotation is relatively fast for an asteroid (5.34 H). Vesta is the second most massive body in the asteroid belt, although it is only 28% the size of Ceres. To give you an idea of its size it is about equal to Pakistan or Nigeria. The biggest craters on Vesta are quite astonishing: eg, Rheasilvia is 500 km wide and 19km deep. The troughs, too, are stunning in size: Divalia Fossae’s biggest dwarfs the Grand Canyon. It is 465 km long and up to 12 km wide.

_{Astropark, Sai Kung}

A good place to view Vesta, away from most light pollution, would be Sai Kung’s Astropark, below the west cofferdam at High Island reservoir. The Astropark is equipped with Chinese and western astronomical instruments so you can gaze with wonder at a shining asteroid commemorating a Roman goddess.