A Binary Asteroid

This image  was taken by the Long-Range Reconnaissance Imager (L’LORRI) aboard the Lucy spacecraft as it flew by the asteroid Dinkinesh. It shows a satellite as it emerges from behind the primary asteroid. This image was taken at 1655 UTC on 1 November from a range of about 430 km. From this perspective, the satellite is behind the primary asteroid. The image has been processed to enhance contrast.

Image Credit: NASA / SwRI/ APL / NOIRLab

Ida and Dactyl

The Galileo spacecraft was en route to Jupiter in 1993 when it encountered this pair of asteroids, 243 Ida is 60 km long x 25 km wide and had been seen with Earth-based telescopes. When it was photographed by Galileo, it was unexpectedly discovered to have a moon. Its tiny moon Dactyl is only about 1.6 kilometers across and was the first moon of an asteroid ever discovered.

Image Credit: NASA

Eyes on Asteroids

NASA has a new 3D real-time visualization tool you can use toexplore the asteroids and comets that approach Earth’s orbit. Eyes on Asteroids also tracks several spacecraft on asteroid related missions and brings this data to any smartphone, tablet, or computer with an internet connection.

The web-based app plots the orbits of every known Near Earth Object and shows detailed information on thems. Using the slider at the bottom of the screen, you can travel quickly forward and backward through time to see their orbital tracks. The database receives twice-daily updates with the latest data, so as soon as a new object is discovered and its orbit is calculated, it’s added to the app.

Image Credit: NASA


idamoonThis color mosaic shows the asteroid Ida and its moon Dactyl. The images use to assemble this picture were taken by the camera system on the Galileo spacecraft as it was passing through the Asteroid Belt in 1993. Ida is about 52 km in length and, as you can see, is irregularly shaped. The image shows many craters, including quite a few degraded ones, indicating Ida’s surface is older than previously thought.

Dactyl was discovered in the series of images Galileo recorded over an observation period of 5.5 hours during the 1993 flyby of Ida. Dactyl’s longest dimension is about 1.6 km.

Image Credit: NASA

Hygiea, Vesta, and Ceres

New ground-based observations with ESO’s SPHERE instrument on the Very Large Telescope have revealed that the surface of the asteroid Hygiea lacks a large impact crater. Because it was formed from one of the largest impacts in the history of the asteroid belt, astronomers were expecting to find at least one large, deep impact basin, similar to the one on Vesta (bottom right in the central panel).

The new study also found that Hygiea is spherical. That would mean that it rather than Ceres is the smallest dwarf planet in the Solar System. Hygiea’s diameter is just over 430 km, a bit less than half that of Ceres (950 km).

Image Credit: ESO

A Near Earth Asteroid

NearEarthAsteroidThe greenish-yellow dot in the upper left is the potentially hazardous near-Earth object 1998 KN3 moving past a cloud of dense gas and dust near the Orion nebula in the far, far background. NEOWISE, the asteroid-hunting portion of the Wide-field Infrared Survey Explorer, or WISE, mission, took this infrared picture. Because near-Earth asteroids are warmed by the Sun to roughly room temperature, they glow brightly at the infrared.

Infrared light from asteroids is used to measure their sizes. Combined with visible-light observations, that data can also measure the reflectivity of their surfaces. The WISE data reveal that this asteroid is about 1.1 km in diameter and reflects only about 7 percent of the visible light that falls on its surface. It is relatively dark.

In this image blue denotes shorter infrared wavelengths and red, longer. Hotter objects emit shorter-wavelength light; they appear blue. Stars with temperatures of thousands of degrees are blue. The coldest gas and dust are red. The asteroid appears greenish-yellow in the image because it is about room temperature—cooler than the stars, but warmer than the dust.

Image Credit: NASA


This animation shows the first four year’s progress of NASA’s Near-Earth Object Wide-field Survey Explorer (NEOWISE) mission following the repurposing of the WISE satellite in December, 2013. Green dots represent near-Earth objects. Gray dots represent all other asteroids which are mainly in the main asteroid belt between Mars and Jupiter. Yellow squares represent comets.

Image Credit: NASA


These detailed images were taken by ESO’s Very Large Telescope at the Paranal Observatory in Chile. Clockwise from top left, the asteroids shown here are 29 Amphitrite, 324 Bamberga, 2 Pallas, and 89 Julia.

2 Pallas was named after the Greek goddess Pallas Athena and is about 510 km wide. It’s the third largest asteroid in the main belt and one of the biggest asteroids in the entire Solar System. It contains about 7% of the mass of the entire asteroid belt andt was once classified as a planet.

89 Julia is about one-third the size of Pallas. It’s classified as a stony or S-type asteroid, as is 29 Amphitrite. 324 Bamberga, one of the largest carbonaceous or C-type asteroids in the asteroid belt. C-type asteroids may actually be bodies from the outer Solar System which followed the migration of the giant planets inward.

In total, the asteroid belt contains just 4% of the mass of the Moon, with about half of this mass contained in the four largest: the dwarf planet Ceres, 4 Vesta, 2 Pallas, and 10 Hygiea.

Image Credit: ESO

Asteroid Photobombing

This Hubble image of a random patch of sky is part of a survey called Frontier Fields and was assembled from multiple exposures. It contains thousands of distant galaxies and the trails of asteroids moving through the field of view. The asteroid trails appear as curved or streaks. The combined image show 20 sighting of 7 different asteroids.

Image Credit: NASA / ESA / STScI

Radar Astronomy and Asteroids

2017bq6Astronomers use large radio telescopes as radar sets to look at nearby objects in space. These images of asteroid 2017 BQ6 are from data collected using the Goldstone Solar System Radar in the Mojave Desert. The images were taken on 7 February as the asteroid flew by about 2.5 million km from Earth. The asteroid is about 200 m across and has an unusually squared off shape.

Image Credit: NASA


VLT Sees NEONEOs are asteroids or comets that come very close to the Earth’s orbit. More than 600,000 asteroids are known in the Solar System, and more than 10,000 of them are NEOs. Their sizes range from metres to tens of kilometres. Some NEOs could hit our planet and, depending on their size, produce considerable damage. While the chance of a large object hitting the Earth is very small, it could produce a great deal of destruction and loss of life—as the dinosaurs discovered 50 million or so years ago.

Up to now the asteroid 2009 FD had been ranked among the top five objects in a list of the most dangerous objects, but new observations with ESO’s Very Large Telescope (VLT) have now shown that it is far less likely to hit the Earth than had been feared. The calculations show there is still a small chance of an impact between the years 2185 and 2198.

Image Credit: ESO