What's that mysterious object spotted near Mercury?

What's that mysterious object spotted near Mercury?

A camera onboard NASA's Stereo spacecraft recorded a wave of electrically charged material shooting out from the sun and blasting Mercury. Footage of this "coronal mass ejection" (CME), as such events are called, has caught the attention of alien-hunters, who say it has unveiled a giant, "cloaked" spaceship parked near the solar system's innermost planet.

In the footage, one sees a huge spurt of plasma and other solar ejecta washing over Mercury; peculiarly, the material seems to flare up as it hits another nearby object, too. "It's cylindrical on either side and has a shape in the middle. It definitely looks like a ship to me, and very obviously, it's cloaked," YouTube-user siniXster said in his video commentary on the footage, which has quickly spread across the Web.

The commentator says there's "absolutely no explanation" for the nearly Mercury-size mystery object other than that it's a spaceship. "What object in space cloaks itself and doesn't appear until it gets hit by energy from the sun?" siniXster asked.

The question was meant rhetorically, but nonetheless, the video is curious, so we've put it to scientists in the solar physics branch at the United States Naval Research Laboratory (NRL) — the group that analyzes data from the Heliospheric Imager-1 (HI-1), the telescopic camera that shot the new footage.

As you might suspect, there is a non-UFO explanation of the apparent flare-up near Mercury. According to Russ Howard, head scientist of the NRL group, and Nathan Rich, lead ground systems engineer, it is simply an artifact left over from the way raw HI-1 telescope data gets processed. Rather than a UFO mothership parked near Mercury, the bright spot is "where the planet was on the previous day," Rich told Life's Little Mysteries.

To make the relatively faint glow of a coronal mass ejection stand out against the bright glare of space — caused by interplanetary dust and the stellar/galactic background — the NRL scientists must remove as much background light as possible. They explained that they determine what light is background light, and thus can be subtracted out, by calculating the average amount of light that entered each camera pixel on the day of the CME event and on the previous day. Light appearing in the pixels on both days is considered to be background light and is removed from the footage of the CME. The remaining light is then enhanced.

This works great for objects far off in the distance, such as stars, which don't move much relative to the sun. But it gets a little trickier when trying to account for nearer objects, particularly moving ones, like planets.

 What's that mysterious object spotted near Mercury?