19 June 2010

The Path That Leads to the Earth's Shadow

We are in an "Eclipse Season," a five week period of time when the Moon's orbit around the Earth is aligned in a way that the Full or New Moon crosses the path of the Earth around the Sun. When that happens, we experience a Lunar or Solar Eclipse and right now we have one of each coming up: a partial Lunar Eclipse on Saturday 26th, and a total Solar Eclipse on July 11th. The Solar Eclipse will not be visible from North America so we don't get a chance to experience that, but the Lunar Eclipse will be. More on that next week.
During an Eclipse Season, the Moon's position in the sky is special, as it is moving just above or just below the plane of the planets (the "Ecliptic") in the interval from New Moon to Full Moon. A few days ago as the Moon emerged from the evening glare waxing each evening, you could see it move just below Venus, then below Regulus and Mars, and now it is below Saturn and Spica, all objects on or near the Ecliptic. As it nears Full Moon and the Lunar Eclipse on the 26th, it is moving closer and closer to the Ecliptic and will intersect the Earth's shadow on the 26th.
I like to imagine that there is a dark spot in the sky where the Earth's shadow projects out into space. Every month as the Moon nears Full, it sweeps close to that spot. But only during an Eclipse Season -- every six or twelve months -- does it slip into the shadow of the Earth and display to all of us the curved shadow of the Earth. That is something to look forward to next weekend.

11 June 2010

Heavenly Line-Up

Over the past months the evening sky has been graced by a number of bright stars and planetary configurations. As summer approaches and these stars and planets move westward toward the sunset day after day, heavenly line-ups are emerging that are beautiful to see and are dynamic in nature, changing dramatically from one day to the next.

This evening the planet Venus moves into a very impressive alignment with the two “twin” stars of Gemini, Castor and Pollux. Although Venus is considerably brighter than the two stars, the pattern of the three celestial objects will be distinct, emerging from the sunset glow with Venus as the guide star and Castor and Pollux shining a short while later.

On the 13th and 14th, the trio is joined by the young crescent Moon. The combination of these heavenly bodies in the twilight should be an impressive sight indeed.

04 June 2010

KFOG Podcast - June 4, 2010

Today I spent a few minutes talking with Irish Greg of the KFOG Morning Show for their podcast series. Greg is one of those people with boundless enthusiasm and an insatiable appetite for discussion about any topic, so when we talk astronomy it's always a good time. Today's conversation ranged from the Summer Solstice to the upcoming lineup of Mars and Venus and some bright stars, to the June 26th Lunar Eclipse and the Search for Extraterrestrial Intelligence (SETI). Click here to listen.