solar system

Close Conjunction of Venus and Jupiter on June 30, 2015

June 24, 2015 by Brian Ventrudo Filed Under: Solar System

Venus, Jupiter, and the crescent Moon in the western sky after sunset on June 19, 2015. The two bright planets will come within 0.3 degrees of each other on June 30, 2015.

The bright planets Venus and Jupiter have been moving closer together for weeks, and on June 30, 2015, they make their closest approach when they pass less than a full-Moon-width from each other in the western sky after sunset. This beautiful conjunction of two bright planets is an ideal time for a photo-op and an great opportunity to see the clockwork motion of the solar system in action.

The two planets will fit together in the same low-power field of view in a telescope, and remarkably, they will appear the same size. Venus is a tiny crescent, bright and featureless, while Jupiter displays cloud bands and its four biggest moons. While each spans about 32 arc-seconds in apparent size, in real terms Jupiter is 12x larger and 12x farther away. If the skies are in your favor, wander out and see this remarkable conjunction in the western sky after sunset on June 30 and July 1. It’s visible from the northern and southern hemispheres.

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Saturn at Opposition 2015

May 20, 2015 by Brian Ventrudo Filed Under: Solar System

Saturn at the 2014 opposition as imaged by Damian Peach (damianpeach.com)

The planet Saturn reaches opposition on May 22, 2015. It rises as the Sun sets and makes its closest approach to Earth this year. The planet is as bright as it’s been in eight years, with rings dramatically tilted towards our point of view. This is your best chance in many years to see this beautiful planet in a telescope and share a view of it with others.

Saturn lies well south of the celestial equator this observing season near the border between the constellations Libra and Scorpius in the southeastern sky (as seen from the northern hemisphere) and the eastern sky (as seen from the southern hemisphere). At magnitude 0.0 in late May and early June, Saturn is the brightest object in that part of the sky. It outshines even the brilliant red-orange star Antares to the east. By 10 p.m., you can see the planet low over the horizon, nestled near the three bright stars in the head of Scorpius. You can watch the planet’s motion relative to these stars from night to night over the next few months. It’s been moving ‘in retrograde’ a little westward each day, over and above its daily westward motion. It resumes its normal eastward motion relative to the background stars on August 2 [Read more…] about Saturn at Opposition 2015

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See the Eta Aquariid Meteor Shower

April 27, 2015 by Brian Ventrudo Filed Under: Solar System

An Eta Aquariid meteor over the Devil's Tower in Wyoming (credit: David Kingham) — An Eta Aquariid meteor over the Devil’s Tower in Wyoming (credit: David Kingham)

The usually reliable Eta Aquarid meteor shower peaks on the night of May 5-6 this year. The shower runs from April 21 – May 20, 2015, with many meteors still visible for several days on either side of the peak. It is perhaps the best meteor shower of the year for southern hemisphere stargazers.

The annual Eta Aquarids occur as Earth passes through an stream of icy and dusty debris from the famous Comet 1/P Halley, more commonly called Halley’s Comet. We pass through a second stream of the comet in late October. This results in the Orionid meteor shower. So if you missed the comet during its last apparition in 1986, you can at least see sand-grain-sized bits of the comet burn up in the atmosphere during these two meteor showers.

The Eta Aquarids gets its name from the 4th magnitude star Eta Aquarii in the constellation Aquarius. The star is 168 light years away and bears no physical relation to the meteor shower. But the meteors appear to trace their paths back to a point in the sky near this star as the Earth moves into the debris field.

Because Aquarius lies on the ecliptic well south of the celestial equator, this is a better meteor shower for observers in the southern hemisphere. Rates of 30-60 meteors per hour are typical. Northern stargazers can see perhaps half as many near peak, but it’s still an impressive event. The Eta Aquarids on average are quite speedy and enter the atmosphere at 66 km/s (148,000 mph).

As with most meteor showers, the hours before ~~twilight~~ dawn, as the Earth turns into the meteor stream, are the best time to see the Eta Aquarids. You don’t need to find the star Eta Aquarii to see the meteors. They can appear anywhere in the sky. You don’t need any optics… just lie back under dark sky and look up.

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April 30 – A Big Day for Mercury

April 17, 2015 by Brian Ventrudo Filed Under: Solar System

A photo mosaic of Mercury's northern plains, taken from orbit by NASA's Messenger spacecraft. (Credit: NASA/Johns Hopkins University) — A photo mosaic of Mercury’s northern plains, taken from orbit by NASA’s Messenger spacecraft. (Credit: NASA/Johns Hopkins University)

Just as the planet Venus passed close to the Pleiades last week, the smaller and more elusive planet Mercury will also skim this star cluster on the evening of April 30. The planet and cluster will be low in the northwestern sky after sunset, about 10º above the horizon in the northern hemisphere. This is a golden opportunity to spot the little planet before it heads back towards the Sun. And more remarkably, on the same day, NASA’s MESSENGER spacecraft, which has been orbiting Mercury for four years, will crash into the planet at more than 8,000 mph and end its long mission.

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