Featured Research

from universities, journals, and other organizations

RHESSI will use Venus transit to improve measurements of the sun's diameter

Date:
June 4, 2012
Source:
NASA/Goddard Space Flight Center
Summary:
With the new data obtained during the Venus transit on June 5-6, 2012, the RHESSI team hopes to improve the knowledge of the exact shape of the sun and provide a more accurate measure of the diameter than has previously been obtained.

Artist rendition of RHESSI spacecraft in orbit.
Credit: NASA

The RHESSI (Ramaty High Energy Solar Spectroscopic Imager) satellite focuses on the highest energy x-rays and gamma-rays produced by the sun, helping to observe solar flares of all shapes and sizes. The satellite is pointed toward the sun, and constantly in rotation, which provides a serendipitous bit of side research: by monitoring the limb of the sun on its four second rotation cycle, RHESSI’s Solar Aspect System (SAS) has produced ten years worth of precise measurements of the sun's diameter.

Related Articles


This has already provided scientists with one of the most accurate measurements of what's called the oblateness of the sun, which is the difference between the diameter from pole to pole and the equatorial diameter. With the new data obtained during the Venus Transit on June 5-6, 2012, the RHESSI team hopes to improve the knowledge of the exact shape of the sun and provide a more accurate measure of the diameter than has previously been obtained.

For one thing, the sharpness of the Venus disk as it crosses the sun will help determine the detailed optical properties of the telescope and calibrate the instrument’s so-called plate scale, the exact angular size of each pixel. With this improvement in hand, RHESSI can re-calibrate its already highly accurate observations of the sun's horizon. To further this aim, the science team has set the instrument to look at 64 pixels across the sun's limb, rather than its customary four.

The RHESSI team has hopes that they may be able to provide an unprecedentedly accurate measurement of the sun's size.

With ten years of solar diameter measurements as well as observations of the Venus Transit in 2004 – a time when the sun's activity was decreasing toward solar minimum, as opposed to now when the solar activity is increasing as it moves toward solar maximum predicted for 2013 – the science team hopes to compare the sun's size then and now to see if perhaps it varies with the solar cycle.


Story Source:

The above story is based on materials provided by NASA/Goddard Space Flight Center. Note: Materials may be edited for content and length.


Cite This Page:

NASA/Goddard Space Flight Center. "RHESSI will use Venus transit to improve measurements of the sun's diameter." ScienceDaily. ScienceDaily, 4 June 2012. <www.sciencedaily.com/releases/2012/06/120604182029.htm>.
NASA/Goddard Space Flight Center. (2012, June 4). RHESSI will use Venus transit to improve measurements of the sun's diameter. ScienceDaily. Retrieved April 25, 2015 from www.sciencedaily.com/releases/2012/06/120604182029.htm
NASA/Goddard Space Flight Center. "RHESSI will use Venus transit to improve measurements of the sun's diameter." ScienceDaily. www.sciencedaily.com/releases/2012/06/120604182029.htm (accessed April 25, 2015).

Share This


More From ScienceDaily



More Space & Time News

Saturday, April 25, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Hubble Telescope: 25 Years Of Revealing The Universe

Hubble Telescope: 25 Years Of Revealing The Universe

Newsy (Apr. 24, 2015) Despite a blurry start to its service, the Hubble Space Telescope is still serving as one of the best visual science tools on or off the planet. Video provided by Newsy
Powered by NewsLook.com
Hubble Telescope Celebrates 25th Anniversary

Hubble Telescope Celebrates 25th Anniversary

AP (Apr. 23, 2015) NASA&apos;s Hubble Space Telescope is celebrating its 25th anniversary of being placed into orbit. NASA unveiled the official Hubble anniversary image to mark the occasion. (April 23) Video provided by AP
Powered by NewsLook.com
The Hubble Turns 25

The Hubble Turns 25

Reuters - US Online Video (Apr. 22, 2015) The Hubble telescope turns 25, marking a milestone in the history of space exploration. As Pavithra George reports, NASA is celebrating the technology, saying Hubble has "rewritten the text books." Video provided by Reuters
Powered by NewsLook.com
Teens Compete, Help Shape Future of NASA

Teens Compete, Help Shape Future of NASA

AP (Apr. 21, 2015) This week, 17,000 students from 30 countries are competing in the 20th FIRST Robotics Championship in St. Louis, including a team from Houston that, a few years ago, helped influence the design of a NASA rover. (April 22) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins