Herschel solves mystery of Jupiter's water!!

(news courtesy ESA)

Shoemaker-Levy 9 impact site G

24 April 2013

Jupiter, the largest planet in the Solar System, is mostly made of the gases hydrogen and helium. Tiny amounts of water have been found in its upper atmosphere, but, until now, no one was sure where this water came from. The answer to the long-standing mystery has been given by ESA’s Herschel space observatory, the most sensitive infrared telescope ever launched. Herschel has found conclusive evidence that the water was delivered by multiple comet impacts in July 1994!

Collisions with incoming cosmic debris are a continuous threat to the planets of the Solar System, including Earth. However, few impacts have actually been observed by scientists. The first direct observation of such an event occurred at Jupiter, 19 years ago. Astronomers watched in astonishment as 21 pieces of comet Shoemaker-Levy 9 plunged into the planet’s upper atmosphere and exploded.

Water in Jupiter's Atmosphere

ESA’s Infrared Space Observatory, launched in 1995, was the first to detect and study water in Jupiter's upper atmosphere. Scientists were able to exclude an internal source, such as water rising from below. But if the water was delivered from outside, where did it come from?

It was widely speculated that comet Shoemaker-Levy 9 may have been the origin of this water, but direct proof was missing. Now Herschel’s sensitive infrared eyes have solved the mystery. The space observatory has found 2-3 times more water in the southern hemisphere of Jupiter than in the northern hemisphere. The traces of water are only found at high altitudes and most of it is concentrated around the sites of the 1994 comet impacts.

Even more detailed observations of the gases that make up Jupiter’s massive atmosphere will be made by ESA’s JUICE mission, which is planned for launch towards the giant world in 2022.

Comets can do so much and more!! 

Here come the Perseids!

Here come the Perseids!
(news courtesy ESA)

Perseids meteor shower (Credits: Ali Jarekji, Reuters)

1 August 2013

Sky watchers will be in for a treat in mid-August, when the annual Perseid meteor shower reaches its peak! If you have never before seen a meteor, this is the ideal opportunity. The shower lasts from late July until 20 August, with maximum activity expected between 11 and 13 August. The sky will be dark, as the crescent Moon will be setting below the horizon in mid-evening. And the night should also be warm, so you won’t even need to wrap up! Just keep away from bright lights, let your eyes adapt to the darkness, then lie back and stare at the sky.

Perseids are named after the constellation of Perseus, from which they seem to radiate outwards. However, they can appear anywhere in the sky. The best direction to look is wherever your sky is darkest, probably straight up. The constellation is low in the north-northeast before midnight and rises higher above the horizon during the early morning. The shower is best observed from 11 pm or midnight onward, when you may see 60-100 meteors per hour.

Credits: NASA

The Perseids are sand - to pea - sized bits of rocky debris that were ejected long ago by comet Swift-Tuttle. The comet is slowly disintegrating as it orbits the Sun. Over the centuries, its crumbly remains have spread along its orbit to form a stream of particles hundreds of millions of kilometers long.

Earth’s path around the Sun carries us through this comet debris every mid-August. The particles, or meteoroids, are travelling at 60 km per second with respect to Earth. When one of them hits the upper atmosphere, it creates a white-hot streak of super-heated air. Occasional brighter ones may survive for several seconds, leaving short-lived trails of glowing smoke and gas.

The Perseids are ideal for digital imaging. Attach your camera to a tripod, preferably with a wide angle lens and a high ISO (darkness) setting. Keep the shutter open for 10-15 seconds at a time (longer in a really dark place). With a bit of luck, you should capture one or more Perseids streaking across the photo!

Enjoy observing the August Night Sky!!