If you’re out at dawn the next two mornings you’ll see a lovely sight in the southeastern sky as the crescent moon passes near the planet Venus. Tomorrow it will lie some six degrees to the right of the planet, while on Tuesday the crescent will be four degrees to the left.
Venus, while still brilliant, has been steadily drawing closer to the sun over the past month as its distance from Earth increases and the angle it makes between us and the sun diminishes. At the same time, the planet’s phase waxes from ‘half moon’ to gibbous. A small telescope will easily show its egg-like outline.
Because Venus is perpetually shrouded in highly reflective clouds, we never see its surface. Amateur astronomers using special ultraviolet filters can photograph textures in the clouds, but they’re rarely seen visually. Overcast skies combined with Venus’ relative closeness to Earth are the reasons it’s the brightest planet.
Astronomers rank how reflective an object is by its albedo (al-BEE-do). A body that reflects 100% of the light it receives has an albedo of 1. Venus’ albedo is .75 so it reflects 75% of the light it receives from the sun. In contrast, the coal-dark moon reflects only 12% of the sunlight falling on it. The brightest object in the solar system is Saturn’s icy moon Enceladus with an albedo of .99.
Curious about Earth? Dark soil reflects about 5% of sunlight and virgin snow 95%. Averaged out, our planet’s albedo is .37Â – a dim world compared to Venus.
I’m very happy to share this spectacular photo taken byÂ MÃ³nika Landy-GyebnÃ¡r
of Veszprem, Hungary yesterday evening. Unlike U.S. observers, Monika got to see the space station and Discovery shuttle in the evening sky shortly before they docked.
She describes the scene: “The spacecraft were at about 1/4 degree separation, so really close! I’m unable to describe how beautiful they were! It was the greatest experience I had since the total solar eclipse of 1999.”
The trails of the spacecraft are broken into segments, because MÃ³nika shot multiple exposures, each 1.3 seconds long, which she later combined into a complete trail. One-quarter of a degree is just half the width of the full moon, so that’s amazingly close. I can only imagine the sight! If you didn’t or couldn’t see it, don’t fret. We’ll have another opportunity when the two craft part before the shuttle returns next Sunday.
“It’s taken many years and many hundreds of frames to get an image of the shuttle like this,” said Bullen in an e-mail this afternoon.Â “I regularly image the station but have never been able to get as clear an image of the shuttle as I did last night (it usually just looks like a bright shapeless blob attached to the station).”
Rob and MÃ³nika, we appreciate your efforts and thank you for sharing the results with our readers.
As long as we’re on the topic, I hope you got to see the bright pass of ISS-Discovery Saturday night. More information on upcoming passes can be found in yesterday’s blog.
I finally caught the solar sail NanoSail-D last night. Hah! Just barely. My vigil for this hard-to-catch satellite took place in the frozen wastes north of Duluth where the sky was very dark. I watched for anything along its path from Andromeda through Aries and into Cetus and caught one brief, bright, 1st magnitude flash to the west of Aries. That was it! Our next chance to see it will be Monday. I’ll post a finder map tomorrow.