Space observations of Mercury transits yield precise solar radius

Mar 21, 2012
Mercury's path across the solar disk as seen from SOHO on November 8, 2006. Credit: NASA.

(PhysOrg.com) -- A group of scientists from Hawaii, Brazil and California has measured the diameter of the Sun with unprecedented accuracy by using a spacecraft to time the transits of the planet Mercury across the face of the Sun in 2003 and 2006.

They measured the Sun’s radius as 696,342 km (432,687 miles) with an uncertainty of only 65 km (40 miles). This was achieved by using the solar telescope aboard a NASA satellite, thereby bypassing the blurring caused by Earth’s atmosphere that occurs when observations are made from the ground.

The measurements of the Sun’s size were made by University of Hawaii Institute for Astronomy Drs. Marcelo Emilio (visiting from Ponta Grossa, Brazil), Jeff Kuhn and Isabelle Scholl in collaboration with Dr. Rock Bush of Stanford University. They used the Michelson Doppler Imager (MDI) aboard NASA’s Solar and Heliospheric Observatory (SOHO) to make the measurements.

“Transits of occur 12-13 times per century, so observations like this allow us to refine our understanding of the Sun’s inner structure, and the connections between the Sun’s output and Earth’s climate,” said Kuhn.

The team is preparing to observe the transit of Venus across the Sun on June 5. They expect these observations will improve the accuracy of their solar size measurement even further.

Their scientific paper, which has been accepted by the Astrophysical Journal, is available here.

Explore further: Meteorites yield clues to Martian early atmosphere

Provided by University of Hawaii

5 /5 (1 vote)
add to favorites email to friend print save as pdf

Related Stories

Sun's constant size surprises scientists

May 13, 2010

(PhysOrg.com) -- A group of astronomers led by the University of Hawaii's Dr. Jeff Kuhn has found that in recent times the sun's size has been remarkably constant. Its diameter has changed by less than one ...

Rare transit of Mercury

Nov 02, 2006

Scientists from Williams College and the University of Arizona observed Mercury in front of Venus from vantage points on earthbound mountains and with orbiting spacecraft on Wednesday.

Huge coronal hole is sending solar wind our way

Mar 14, 2012

An enormous triangular hole in the Sun’s corona was captured earlier today by NASA’s Solar Dynamics Observatory, seen above from the AIA 211 imaging assembly. This gap in the Sun’s atmosphere ...

Mercury down under

Feb 27, 2012

NASA’s MESSENGER spacecraft, about to wrap up its first full year in orbit around Mercury, captured this view of the planet’s heavily-cratered southern hemisphere on August 28, 2011. Because of its ...

SDO's crazy-looking Sun due to syzygy

Apr 04, 2011

It looks like something is eating the Sun in recent pictures from the Solar Dynamics Observatory — and in recent SDO videos, the Sun suddenly disappears! What is going on? Could it be aliens, Planet X, ...

Recommended for you

Red moon at night; stargazer's delight

10 hours ago

Monday night's lunar eclipse proved just as delightful as expected to those able to view it. On the East Coast, cloudy skies may have gotten in the way, but at the National Science Foundation's National Optical ...

Meteorites yield clues to Martian early atmosphere

13 hours ago

(Phys.org) —Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks. Their study, published ...

Let's put a sailboat on Titan

16 hours ago

The large moons orbiting the gas giants in our solar system have been getting increasing attention in recent years. Titan, Saturn's largest moon, is the only natural satellite known to house a thick atmosphere. ...

Image: Rosetta's Philae lander snaps a selfie

16 hours ago

Philae is awake… and taking pictures! This image, acquired last night with the lander's CIVA (Comet nucleus Infrared and Visible Analyzer) instrument, shows the left and right solar panels of ESA's well-traveled ...

User comments : 0

More news stories

Meteorites yield clues to Martian early atmosphere

(Phys.org) —Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks. Their study, published ...

Let's put a sailboat on Titan

The large moons orbiting the gas giants in our solar system have been getting increasing attention in recent years. Titan, Saturn's largest moon, is the only natural satellite known to house a thick atmosphere. ...