Astronomy Now Home
Home Magazine Resources Store

On Sale Now!



The October 2014 issue of Astronomy Now is on sale! Order direct from our store (free 1st class post & to UK addresses). Astronomy Now is the only astronomy magazine specially designed to be read on tablets and phones. Download the app from Google Play Store or the Apple App Store.



Top Stories



Earthshine used to test life detection method
...By imagining the Earth as an exoplanet, scientists observing our planet's reflected light on the Moon with ESO's Very Large Telescope have demonstrated a way to detect life on other worlds...
  READ MORE

Solid buckyballs discovered in space
...Astronomers using NASA’s Spitzer Space Telescope have detected a particular type of molecule, given the nickname “buckyball”, in a solid form for the first time...
  READ MORE

Steamy water-world gets the Hubble treatment
...Hubble Space Telescope observations of a 7 Earth-mass planet find an unusual water-rich world swathed in a thick, steamy atmosphere...
  READ MORE








Second smallest exoplanet found by Keck
DR EMILY BALDWIN
ASTRONOMY NOW
Posted: 08 January 2010


Bookmark and Share

An exoplanet only four times the mass of Earth – the second smallest planet in the exoplanet inventory – has been discovered by astronomers using the Keck Observatory in Hawaii.

“This is quite a remarkable discovery,” says astronomer Andrew Howard of the University of California at Berkeley. “It shows that we can push down and find smaller and smaller planets.” The announcement was made at the American Astronomical Society meeting held this week in Washington DC.

Artist impression of an exoplanet on a tight orbit around its host star. Image: NASA, ESA, and G. Bacon (STSci).

The planet, known to astronomers as HD156668b, speeds around its parent star in just over four days, and was detected using the radial velocity technique. This relies on Keck’s High Resolution Echelle Spectrograph on the ten-metre telescope, which records the star's spectrum such that as the planet heads away from us towards the star its spectrum shifts towards redder wavelengths; when it moves towards the Earth the spectrum shifts to bluer wavelengths.

By looking at the colour shifts in the spectrum astronomers can determine characteristics of the planet, like its mass – just four times the mass of Earth in the case of HD156668b. Many of the 400 exoplanets discovered to date are Jupiter-mass planets.

“It’s been astronomers long-standing goal to find low mass planets, but they are really hard to detect,” says Howard. “There are important pieces, we don’t have yet. We need to understand how low mass planets, like super-Earths, form and migrate.”

The discovery will contribute to studies of how planets and planetary systems form and evolve.

HD156668b is located approximately 80 light years from Earth in the direction of the constellation Hercules. The discovery was made as part of the Eta-Earth Survey for Low Mass Planets, which has so far uncovered two near-Earth planets.

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.
 GET YOUR COPY

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.
 GET YOUR COPY

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!
 GET YOUR COPY


HOME | NEWS ARCHIVE | MAGAZINE | SOLAR SYSTEM | SKY CHART | RESOURCES | STORE | SPACEFLIGHT NOW

© 2014 Pole Star Publications Ltd.