Nova update, new radar pix of asteroid 2005 WK4, a phony double star

AAVSO chart for binocular users showing the nova and comparison star magnitudes. Click to download a full-size version. Copyright: AAVSO

Before we embark on today’s topic, let’s update where we’re at with Nova Delphini 2013. For the past day it’s plateaued around magnitude 5.0, maybe even rising a tad to 4.9. It remains easily visible in binoculars high in the southeastern sky at nightfall.

Light from the nearly full moon now drenches the sky, making it nearly impossible to glimpse the nova with the naked eye. Dark skies return about Aug. 23. Let’s hope it hangs in there till then.

On August 8 NASA scientists used the 230-foot (70-meter) Goldstone radar antenna in Goldstone, Calif. to bounce radio waves off near-Earth asteroid 2005 WK4.

Sequence of radar images of 2005 WK4 obtained on August 8 at Goldstone. The asteroid looks roughly oval-shaped with a bulge near the equator and some flat regions. Click for large image. Credit: NASA/JPL-Caltech/GSSR

By studying the reflected radar echoes, they reconstructed a sequence of images of the giant boulder, estimated at between 660 and 980 feet (200-300 m) in diameter. In a delightful coincidence that’s about as big as the 1,000-foot Arecibo radio telescope in Puerto Rico, the largest in the world. Astronomers used this dish to observe 2005 WK4 in July 2012.


Video of 2005 WK4 on Aug. 7 by Gianluca Masi. The asteroid appears only as a point of light in even the largest optical telescopes. The radar technique not only gives precise positions of nearby asteroids but also reveals their shapes and surface features

The asteroid missed Earth by a long shot - 1.93 million miles (3.1 million km) – but the data gained by radar studies will help refine 2005 WK4′s orbit well into the future. It also transformed what had been a mere point of light into a real world, albeit a small one. The Goldstone sequence covers 6 1/2 hours during which the asteroid completed 2.4 rotations.

The moon and stars Alpha and Beta Capricorni form a right triangle tonight in binoculars. The field of view shown above is about 5 degrees. Stellarium

While you’re out gandering at the nova tonight, give a look at the big, bright moon in your binoculars. About 4-5 degrees to its left on the opposite side of the field of view are two bright stars, Alpha and Beta Capricorni in Capricornus the Sea Goat. Alpha looks like the perfect double star, where you might envision each in orbit around the other. Guess again. It’s a total fake – just a chance alignment that convincingly mimics the real thing.

Below it shines Beta. Here we have a genuine double with a 6th magnitude companion orbiting close by to the west. The moon helps us find Alpha and Beta Cap with ease, but glare could make spotting Beta’s companion a bit of a challenge at least tonight. Give it a try to see for yourself.

1998 QE2 asteroid flyby an opportunity for pros and amateurs alike

Many separate telescopic images were combined to create this animation of asteroid 1998 QE2 moving through a star field this past week. Credit: Ernesto Guido and Nick Howes

An asteroid it would take an hour to walk across will speed past Earth on May 31 and provide radio astronomers a perfect opportunity to nab closeup views of its surface. 1998 QE2, discovered in 1998 by the Massachusetts Institute of Technology Lincoln Near Earth Asteroid Research (LINEAR) program,  will miss our planet by a healthy 3.6 million miles (5.8 million km) or 15 times the distance of the moon. Closest approach occurs at 3:59 p.m. Central time.

The asteroid’s large size combined with its relatively close approach makes it a great target for both the 230-foot (70-m) Goldstone radio dish and 1,000-foot (305-m) Arecibo dish in Puerto Rico. Lance Benner, the principal investigator for the Goldstone radar observations from NASA’s Jet Propulsion Laboratory in Pasadena, Calif., will have all hands on deck for the flyby. By sending bursts of radio waves at 1998 QE2 and measuring the retured radar echoes, Benner expects the dishes to resolve surface features as small as 12 feet (3.75m) across on the 1.7-mile-long asteroid (2.7 km).

The orbit of asteroid 1998 QE2. Its May 31 flyby will be the closest it comes to Earth for at least the next 200 years. Its closest point to the sun is similar to Earth’s; when farthest it’s 353 million miles from the sun in the asteroid belt between Mars and Jupiter. Credit: NASA/JPL-Caltech

Through an ordinary optical telescope, even a large one, 1998 QE2 will appear as a point of light. Radar observations reveal far more including shape, size, rotation and a wide variety of surface features. Goldstone observations are scheduled from May 30 – June 9; those at Arecibo for several days around June 5.

Already optical telescopes in the southern hemisphere have this monster rock in their crosshairs. By measuring repeating highs and lows in the asteroid’s brightness as it spins on its axis, astronomers can determine its rotation rate. 1998 QE2′s composition is gleaned by how it reflects sunlight. Reflected sunbeams streaming back to Earth carry the imprint of particular minerals that absorb and reflect portions of the sun’s light in unique ways that nail down their identities.

“It is tremendously exciting to see detailed images of this asteroid for the first time,” said Benner. “With radar we can transform an object from a point of light into a small world with its own unique set of characteristics. In a real sense, radar imaging of near-Earth asteroids is a fundamental form of exploring a whole class of solar system objects.”

1998 QE2 looks like a point of light in this time exposure taken remotely with a telescope in Australia by the team of Ernesto Guido and Nick Howes. The asteroid is currently very faint and only visible in the southern hemisphere. Click for more on the asteroid in their blog.

I’m excited about the asteroid because it will be bright enough to be visible in small telescopes across both northern and southern hemispheres for several nights around the time of closest approach. Between May 30 and June 5 it will shine at 10.5-11.0 magnitude while chugging through the constellations Libra and Ophiuchus, both conveniently placed at nightfall. Its steady movement across the sky – 2/3 of a full moon diameter an hour – will be obvious through the telescope. Come the end of the month, I’ll create a map to help you find it.

Read more about 1998 QE2 HERE. Amateur astronomers needing orbital elements and ephemerides can check out the Goldstone planner.

Curious about asteroids? Tune in to tonight’s live stream by expert Lance Benner

Nine radar images of near-Earth asteroid 2007 PA8 were obtained between Oct. 31 and Nov. 13, 2012, by NASA’s 230-foot-wide (70-meter) Deep Space Network antenna at Goldstone, Calif. Credit: NASA/JPL-Caltech

Ever wonder how scientists get such detailed radar images of asteroids that only look like points of light in optical telescopes? Tune in tonight or tomorrow night to a talk by Dr. Lance Benner, research scientist at the Jet Propulsion Lab, to find out. Benner will speak on Radar Imaging of Near Earth Asteroids at Pasadena City College; you can watch the real-time webcast and even join the audience for questions after the talk. Both lectures start at 9 p.m. Central (7 p.m. Pacific) time May 9 and 10.

Dr. Lance Benner. NASA photo

Only two radio telescopes on the planet are used for radar imaging of asteroids: the giant 1,000-foot (305 m) Arecibo Observatory in Arecibo, Puerto Rico and the 230-foot (70 m) Goldstone dish in JPL’s Deep Space Network in California’s Mojave Desert. By pinging nearby asteroids with radio waves and studying the reflected radio echoes, these telescopes can resolve details as small as 10 feet (3 m) across.

Radar images can also nail down an asteroid’s rotation rate, measure its position with great precision (allowing for a more precise orbit to be calculated) and “see” features like craters and boulders.

In a related story, Detlef Koschny, Head of Near-Earth Object activities in the European Space Agency’s Space Situational Awareness Programe Office, hopes to improve efforts to find and track near-Earth objects (NEOs) using telescopes operated by European Union members to scan the sky nightly for new Earth-approaching asteroids. The agency is also considering ways of deflecting smaller but still potentially dangerous asteroids should they be found on a collision course with Earth.

“It’s important that we become aware of the current and future position of NEOs, develop estimates on the likelihood of impacts and assess the possible consequences,” says Koschny.

Artist’s view of Earth-approaching asteroids. Many asteroids in this class were originally located a safe distance away in the asteroid belt between Mars and Jupiter, but collisions between them created fragments that were later perturbed by the planet Jupiter into Earth-crossing orbits. Credit: ESA / P. Carril

Of the more than 600,000 known asteroids in the solar system, nearly 10,000 are classified as Near Earth Asteroids because they pass relatively close to our planet. “Near” is defined as any object approaching within 28 million miles of Earth’s orbit.

This week in a meeting in Spain, Deimos Space, an industrial partner working for ESA, invited top researchers from universities, research institutes, national space agencies and industry in Europe and the USA to discuss the state of the art in NEO impact effects and threat mitigation.

There are a variety of methods being considered for changing a potentially hazardous asteroid’s course, and they all critically depend on finding the object well in advance of a collision.

You can hit it with a massive object the way we smacked Comet Tempel 1 with an 815-lb hunk of copper during NASA’s Deep Impact Mission in 2005. If the asteroid’s small enough and impactor massive enough, you could nudge the object off its hazardous course.

Artist view of a spacecraft acting as a gravity tractor nudging an asteroid off-course through mutual gravitational interaction. Earth and moon are off to the right. Credit: Dan Durda/FIAAA/B612 Foundation

Or you could vaporize part of the asteroid with a nuclear weapon, altering its orbit while hopefully not creating additional fragments that could imperil the planet. For obvious reasons, this method would work best with asteroid made of solid rock, not those made of loose “rubble piles”.

Then there’s the gravitational tug method. Here you orbit a large, heavy spacecraft near the asteroid. The mutual gravitational attraction between the two over several years time would change the space rock’s trajectory. A variation on this approach is to fire the spacecraft’s thrusters at the object or even to anchor a rocket engine directly to the asteroid’s surface and blast away, giving it a slow, steady push in the right direction.

Other methods proposed include playing “asteroid paintball” by dusting an NEA with black soot or white powder or even wrapping it in shiny aluminized plastic. Think of how hot you’d feel wearing a black shirt on a sunny day compared to a white one. Absorption or reflection of sunlight can change an asteroid’s rotation rate and nudge it into a slightly different orbit over time.

Expand your knowledge on the topic of asteroids by listening in tonight or tomorrow night to Dr. Benner’s talk. There are actually two ways to connect – the live stream and also via Flash Player with open captioning.

Go for a virtual asteroid ride; seismic activity on 2012 DA14?

Asteroid 2012 DA14, which will pass about 17,200 miles from Earth tomorrow (Fri. Feb. 15) around 1:24 p.m. CST is about 150 feet long or somewhat less than half the length of a football field. Illustration: Bob King using wiki and NASA images

As asteroid 2012 DA14 silently flies toward Earth, how would you like to go along for the ride? Now you can, virtually speaking. NASA has created a simulated display that allows you to accompany the asteroid as it speeds toward the planet. Since the view refreshes every two minutes, you can watch the planet grow larger as the asteroid sweeps in to make its closest approach tomorrow around 1:24 p.m. Central Time. That’s when the real drama will unfold as 2012 DA14 passes just 17,200 miles over Indonesia before speeding back into the depths of space. Click HERE to make the trip.

Although 2012 DA14 won’t impact Earth, the planet’s gravity will leave a potentially strong impression on the asteroid. Besides bending its orbit into a smaller circle with a shorter orbital period during the flyby, it’s possible that the space rock might tremble with tremors or asteroid-quakes.

View from the virtual asteroid tracker looking toward Earth today Feb. 14, 2013 at 1:37 p.m., one day before closest approach. Credit: NASA

“We are going to be looking closely for evidence of seismic activity on 2014 DA14 as it passes by,” says Richard Binzel, a professor of planetary science at MIT. “This is the first case of an object coming close enough to experience quakes AND where we have enough notice to plan observations.”

The Galileo spacecraft captured this “stretched color” view of asteroid 951 Gaspra in 1991. The red color is caused by solar radiation and cosmic rays weathering of the asteroid’s soil. Credit: NASA

A few years ago Binzel noticed a small group of asteroids that didn’t show signs of “space weathering” from bombardment by cosmic rays and solar radiation over the eons. High-energy particles interact with asteroids’ rocky surfaces and cause their soils to turn dark-red.

After studying their orbits, he discovered that all these “fresh-faced” space rocks had had close encounters with the Earth in the past million years.

“We believe they were ‘shaken up’ by their encounters with Earth,” he says. “Gravitational forces during the flybys can stretch, rattle, and torque these asteroids, causing dark, space-weathered material on the surface to be overturned, revealing the fresh stuff underneath.”

NASA’s Goldstone radar dish in California will have its eye trained on the asteroid during tomorrow’s flyby. The dish sends radio waves at the asteroid and measures their echo or reflection upon return to build up a map of its shape. Credit: NASA

2012 DA14′s crust could shift by an inch or two and possibly release a puff of asteroid dust. MIT postdoc Nick Moskovitz, who works with Binzel, is coordinating observations with worldwide observatories to pin down the color, spin, shape, and reflectivity of the asteroid as it passes by. NASA’s 70-meter Goldstone radar dish will also repeatedly ping 2012 DA14 with radio waves and measure the energy reflected back to create a 3D picture of it. If we’re very fortunate, the dish might even see the effects of seismic activity. Read more on the topic HERE.


Nice video about the flyby from NASA’s ScienceCast