Category Astronomy/Space

This image of asteroid 2015 TB145, a dead comet, was generated using radar data collected by the National Science Foundation’s 1,000-foot (305-meter) Arecibo Observatory in Puerto Rico. The radar image was taken on Oct. 30, 2015, and the image resolution is 25 feet (7.5 meters) per pixel. Credit: NAIC-Arecibo/NSF

Scientists observing asteroid 2015 TB145 with NASA’s Infrared Telescope Facility (IRTF) on Mauna Kea, HI, have determined that the celestial object is more than likely a dead comet that has shed its volatiles after numerous passes around the sun.

The first radar images of the dead comet were generated by the National Science Foundation’s 305-meter (1,000-foot) Arecibo Observatory in Puerto Rico...

This is a graphic depicting the orbit of asteroid 2015 TB145. The asteroid will safely fly past Earth slightly farther out than the moon’s orbit on Oct. 31 at 10:05 a.m. Pacific (1:05 p.m. EDT and 17:05 UTC). Credit: NASA/JPL-Caltech

NASA scientists are tracking the upcoming Halloween flyby of asteroid 2015 TB145 with several optical observatories and the radar capabilities of the agency’s Deep Space Network at Goldstone, CA. The asteroid will fly past Earth at a safe distance slightly farther than the moon’s orbit on Oct. 31 at 10:01 am PDT. The flyby of the estimated 1300-ft-wide asteroid is a science target of opportunity, allowing instruments on “spacecraft Earth” to scan it during the close pass.

Asteroid 2015 TB145 was discovered on Oct...

A computer model reproduces the two-spiral-arm structure; the “x” is the location of a putative planet. The planet, which cannot be seen directly, probably excites the two spiral arms. Credit: NASA, ESA, ESO, M. Benisty et al. (University of Grenoble), R. Dong (Lawrence Berkeley National Laboratory), and Z. Zhu (Princeton University)

This idea not only opens the door to a new method of planet detection, but also could offer a look into the early formative years of planet birth. Though astronomers have cataloged thousands of planets orbiting other stars, the earliest stages of planet formation are elusive because nascent planets are born and embedded inside vast, pancake-shaped disks of dust and gas encircling newborn stars, known as circumstellar disks.

The conclusion that planets may betr...

Size comparison between Earth and the exoplanet GJ1214b. Credit: NASA/JPL-Caltech/R. Hurt (SSC)

A nearby exoplanet has an atmosphere that might be similar to Earth’s before life evolved. Scientists have catalogued nearly 2,000 exoplanets around stars near and far. While most of these are giant and inhospitable, improved techniques and spacecraft have uncovered increasingly smaller worlds.

But size alone is insufficient to judge a globe. Though Earth and Venus are nearly identical in size, the latter’s surface is hot enough to melt lead. Astronomers must gather information about an exoplanet’s atmosphere, often through observing how the planet scatters or absorbs light from its parent star. But, that information is not always useful – as is the case with the exoplanet GJ1214b.

“When an exop...