May 25, 2017

AstroEvent: The Best Appearance of Mercury in 2011.

Mercury+Jupiter in the dusk. (Photo by Author).

If you’ve never seen the inner-most world of our solar system, this week is your chance. On Tuesday, March 22nd, the planet Mercury reaches a greatest elongation of 19 degrees east of the Sun.  Due to the varying angle of our ecliptic during different times of the year coupled with an eccentricity of 0.21 for Mercury’s orbit, not all apparitions of the innermost world are equal. [Read more...]

Observing from the ‘Hood’: Good Targets for Bright Skies.

 

 

 

 

Stove Pipe scope ready for action...(Photo by Author).

If you’re like us here at Astroguyz HQ, you find yourself in the ‘burbs under increasingly brightening night skies. But you want to use that shiny new Christmas telescope, right? What follows is a list of objects that you can view tonight from the comfort of your backyard, can of beer and barbeque in hand. This list also serves as a peek at our star party faves, which can frequently occur under less than optimal skies; [Read more...]

AstroEvent: A Challenging Dawn Conjunction.

Saturn & Mercury on closest approach. (Created by the Author with Starry Night).

Saturn & Mercury on closest approach. (Created by the Author with Starry Night).

 

   Set your alarm clocks; one of the closest but most challenging planetary pairings of the year happens this week in the early dawn skies. Mercury and Saturn will be within 1° degree of arc separation the morning of October 8th. Saturn is fresh from superior conjunction behind the Sun, and Mercury is currently undergoing a dawn apparition. Both will fit well in a binocular field of view or a low power eyepiece. The pairing will rise about 45 minutes prior to local sunrise, which for middle northern latitudes will occur around 7:45 AM local. [Read more...]

22.10.09: Thank Relativity that We’re Here!

A very bad day...a Mars sized impactor strikes the Earth! (Credit: J. Vidal-Madjar/IMCCE/CNRS).

A very bad day...a Mars sized impactor strikes the Earth! (Credit: J. Vidal-Madjar/IMCCE/CNRS).

The next time you’re studying the Lorentz equation or are forced to account for Relativity on your Buzzard Ramjet trip to Sirius, thank Einstein that we’re here at all! Scientists Jacques Laskar and Mickael Gastineau at the Paris Observatory have been modeling orbital dynamics in our solar system and have come up with some “disturbing” results. It has long been known that Jupiter has a shepherding effect on the inner solar system, smoothing out planetary orbits while ejecting or sweeping up incoming debris. However, if you model the planetary orbits taking into account only classic Newtonian motion, the odds that Mercury goes out of whack in the Sun’s 10 billion year odd life span are about 60%. Throw in Einstein, and the effect shrinks to less than 1%. A careening Mercury would be a bad thing; if it impacted Venus, we would get showered with debris over a million year span, and if it hit us, well, it would just be a bad day. The best thing it could do is harmlessly impact the Sun. Even a near miss with the Earth could drastically alter our orbit, not to mention tinker with our stabilizing Moon. Fortunately, the tiny tweak that the Sun’s gravitational well gives Mercury’s eccentric orbit via General Relativity assures that a resonance keyhole with Jupiter’s orbit probably won’t happen. Keep in mind, we’re talking tiny effects that pile up over billions of years… every time an asteroid whizzes by, we launch a Space Shuttle, or LeBron performs a slam dunk, the Earth gets a tiny push. Over billions of years, tiny forces do add up (ever heard of the Butterfly Effect?) This is why astronomers cannot predict the positions of planets more than a million or so years into the future. Incidentally, the precession of Mercury’s orbit still stands as one of the great observational proofs of Relativity. One also wonders if such a perturbation might have been the fate of Theia, the Mars sized impactor that has been hypothesized to have struck a prehistoric Earth and created our Moon. So the next time you see gravity bend light at relativistic speeds, thank Einstein for protecting our home planet Earth!

Astro event of the Week, August 12-18, 2008: See a Triple Conjunction!

Alas, poor North America! We miss out of both this months’ eclipses! But I give you as an Astro consolation of sorts; a rare triple planetary conjunction! 

Conjunction.

Looking West, about half an hour after Sunset. (Credit: Stellarium)

    On the evening of August, 15th, the planets Mercury, Venus, and Saturn will span an area of less than 2 degrees, a nice binocular view. [Read more...]