Tuesday, December 29, 2015
Sunday, December 27, 2015
Monday, December 7, 2015
But that brings up occultations that SDO will see. Next year we will see a transit of Mercury across the disk of the Sun on May 9, 2016. Here is a movie of the transit (using our predicted ephemeris, but it should be fairly close.)
Mercury is smaller and further from the Earth, so, compared to the transit of Venus in 2012, it will be a smaller disk as it passes between SDO and the Sun. Due to the shorter orbital period, transits of Mercury are more common than transits of Venus.
Johannes Kepler predicted a transit of Mercury would occur in November 1631. The first observed transit of Mercury was on November 7, 1631 by Pierre Gassendi. This was the first observed planet transit and showed that Kepler's equations of planetary motion could be used to predict the positions of planets.
SDO will provide near-realtime pictures of the Mercury Transit at a dedicated webpage. More details as the time approaches.
While you are waiting, grab your binoculars and go watch Venus disappear behind the Moon!
Thursday, November 5, 2015
When SDO was launched TVs were displaying 720p resolution. In the five years since we have seen TV screens at 1080p and now UltraHD (3840 pixels by 2160 pixels.) This means we can show half of the Sun in full SDO resolution on commercially available screens. As a result, NASA has released a new of 4k ultra-HD movies of SDO imagery. These are also on YouTube. But to get the full impact of the UltraHD resolution you need to download the movies from SVS website.
The SDO webpage also has a list of UltraHD movies. We are planning to start releasing daily UltraHD movies.
If only UltraHD allowed us to show the entire disk of the Sun at the native resolution of the SDO imagers! But that must await the next generation of screens.
Wednesday, October 28, 2015
Monday, October 12, 2015
Friday, October 9, 2015
Wednesday, October 7, 2015
With the extended mission comes calibration maneuvers. The first is an EVE cruciform today from 1800 UTC (2:00 p.m. ET) until 2230 UTC (6:30 p.m. ET). SDO science data will not available during the maneuver but the AIA images on the SDO website will look like the Sun is zooming around in space.
Congratulations to the SDO Team for the successful proposal and winning another two years of watching the Sun and solar activity!
Monday, September 14, 2015
Check it Out!
HelioViewer. The motion of the Sun is caused by the telescope heating up as the Sun rises. SDO cannot run its fine guidance system without seeing the entire Sun. During an eclipse the fine guidance system is turned off and a little while after the eclipse it is turned back on.
Friday, September 11, 2015
NASA's Eclipse webpage showing the path of the solar eclipse. This is the first time a solar eclipse was visible on the Earth during an SDO lunar transit. SDO cannot see the entire solar eclipse because the Earth gets in the way. The Moon was at perigee (closest point to the Earth) for the Full Moon two weeks ago. That means it is at apogee (furthest point from the Earth) for the New Moon on Sunday. The Moon will appear to be a little smaller than average so a total solar eclipse is not possible this month.
On September 28, 2015 a total lunar eclipse will be visible from most of the United States, Europe, South America and Africa. SDO does not see lunar eclipses because we look the other way. Not to worry, SDO will see another Lunar Transit on October 12, 2015 from 1718 – 1733 UTC (1:18 – 1:33 p.m. ET). It will be a grazing transit. Because SDO will not be near midnight Mountain Time, this transit will not be seen at the surface.
I hope you enjoy the Alignment of the Four Most Important Objects in the Solar System.
Friday, August 28, 2015
Here's the latest from Karl Battams: "As I expected, the comet "pulled an ISON". I won't even describe it as a comet any longer. It's a rubble pile." (SunGrazerComets).
We see comets because they evaporate ices and other compounds from their surface. This cools the comet, but makes it disappear. The water ice that comes off the comet quickly turns into Hydrogen and Oxygen atoms. SDO sees comet tails when the oxygen atoms hit the electrons in the corona. We can use the tails to explore the Sun's magnetic field and corona.
Most Kruetz sungrazing comets are too small to make it to perihelion (Comet Lovejoy in December 2012 was the only exception). We can only watch as this comet goes behind the LASCO occulter disks and hope it continues to evaporate and be seen in SDO/AIA images.
Thursday, August 27, 2015
We will try to post images as fast as we can tomorrow afternoon. Perihelion is at 1947 UTC (3:47 pm ET).
Tuesday, August 25, 2015
This picture shows the edge of the Earth against the Sun in AIA 193. You can see the edge of the Earth is rough, where the absorption of the Earth's atmosphere dims but does not block the light. This is different from the lunar transits, such as the one coming up on September 13, where the Moon's edge is very crisp. That transit occurs near the end of that day's eclipse and coincides with a solar eclipse in the far southern parts of the Earth.
Eclipse season is a result of our geosynchronous orbit. We don't like missing the Sun for up to 72 minutes each day. But the constant contact with SDO allows the high speed data downlink we use to bring the Sun to everyone.
Wednesday, August 12, 2015
The next eclipse season starting August 25, 2015, giving us more chances to see the Earth's limb against the Sun. Eclipse season ends September 17.
The next lunar transit on September 13 will have two firsts. The eclipse by the Earth will happen just before the transit and finish while the Moon is still crossing the Sun. At the same time a partial solar eclipse will be visible in the South between Antarctica and Africa. This will be the first time an SDO lunar transit could be seen as a solar eclipse on Earth. The movie of the combined eclipse and transit looks like a race between two spacecraft.
Wednesday, August 5, 2015
Wednesday, July 22, 2015
Wednesday, July 8, 2015
Tuesday, June 30, 2015
Wednesday, June 24, 2015
Tuesday, June 23, 2015
Soon after the flare, another filament rose off the surface. It will probably strike the Earth's magnetosphere tomorrow (June 24). This means the geomagnetic storm will continue for awhile. Great aurora come from these storms, but they also produce energetic particles and currents in ground-based pipelines and electrical wires.
Welcome to the declining phase of Solar Cycle 24!
Thursday, May 28, 2015
Wednesday, May 20, 2015
Tuesday, May 19, 2015
Wednesday, May 13, 2015
Tuesday, May 12, 2015
SDO will perform an IRU Calibration maneuver on May 13, 2015 from 0400 UTC (Midnight) to 1200 UTC (8 a.m. ET). The spacecraft will perform a series of roll, pitch, and yaw maneuvers designed to exercise the ACS. Science data may not be available during this time.
Wednesday, May 6, 2015
Tuesday, May 5, 2015
Friday, May 1, 2015
SDO was launched to study the Sun's magnetic field. It is done a great job of recording the magnetic field, flares, filaments, and coronal holes during the rise of Solar Cycle 24. As Solar Cycle 24 fades SDO will continue to measure and report the magnetic field and what that magnetic field does in the solar atmosphere.
Thanks to the HMI for creating the maps of the magnetic field I used to create these pictures, and many thanks to the entire SDO team for the amazing mission they have run for the last 5 years.
SDO is GO!
Sunday, April 19, 2015
SDO has performed maneuvers the past two Wednesdays. The EVE cruciform on April 8 and the field of view rasters on April 15.
Today SDO was featured in Beakman Jax in the Washington Post and Annapolis Capital. Check it out at You Can with Beakman and Jax website. Look for the April 19, 2015 strip.
Wednesday, April 1, 2015
Many thanks to the FOT and ACS teams for recovering SDO and getting the data flowing again!
Last night at 0551 UTC (0152 a.m. ET), as SDO began the scheduled roll calibration maneuver, the ACS went into Sun-acquisition mode. SDO remains in that mode while the engineers look for the cause. The spacecraft is stable and in contact with the SDO MOC. Science data is not being taken at this time. Updates will be posted when available.
Tuesday, March 24, 2015
Wednesday, March 18, 2015
A recent post on reddit.com asked whether the inside of the Sun would be the loudest place in the solar system.
We see millions of sound waves moving across and through the Sun. They are used to tell us about the inside of the Sun. The waves are excited by convective blobs running into the surface, like the pop you hear when a bubble hits a wall. Blobs are hitting the surface all the time, so sound waves can always be seen in the Sun. Large solar flares can also cause sound waves to ripple across the surface. Other things, such as material falling back onto the surface, might also cause sound waves, but they have not yet been detected. We don’t hear the solar sound waves at Earth because sound cannot travel through a vacuum and space is a really good vacuum. But we do see the waves as changes in the brightness or velocity of the solar surface.
After looking though the post, I interpreted this question as: What would you hear if you could put a microphone into the atmospheres of the solar system and listen to the sound waves? Where is the loudest place in the solar system?
We can and do listen to the sounds in our atmosphere, oceans, and crust. Each has rumbles at frequencies below normal sound (less than 20 Hz) or infrasound. Winds are an important source of infrasound in the atmosphere and oceans. This is easiest to imagine in the oceans. A wind pushes water into a mound on the ocean, which collapses when it gets too heavy. That falling back emits sound waves that can be measured. You also “hear” ships moving along the surface, animals communicating, and earthquakes. Although you don’t hear this when you put your head underwater, this noise is a growing problem, especially for passive sonar. Another example, the infrasound signal from the Chelyabinsk meteor entry was the loudest meteor yet recorded. It was the study of how the waves from the Krakatoa eruption of 1883 were measured in Europe and the U.S.A. that gave us the first theory of sound waves in the Sun.
You don’t hear infrasound because your ears are tuned to the sound waves needed to talk and survive. Below about 1 Hz you don’t really hear the wave so much as feel the wave. So even though the infrasound is loud, you do not sense it as it passes by unless it is really loud. This also means that the threshold of hearing for these sound waves is almost the same as the threshold of pain.
The Sun does not have fast moving winds to generate noise, but it does have convective blobs banging into the surface. They create infrasound at about 3 mHz, a frequency almost 1 million times lower what we use to talk. These sounds waves are observed moving as ripples in the photosphere, the apparent surface of the Sun in visible light.
The loudness of a sound wave can be calculated if either the pressure change or velocity of the sound wave can be measured. Solar sound waves have a measured velocity of about 10 cm/s at the photosphere. Combining that with the density (2.8 × 10-7 g) and sound speed (8.1 × 105 cm/s) at the photosphere, the loudness of these waves is about 103 dB, below the threshold of pain (130 dB), but possibly below the threshold of hearing as well. Even though there are many of these modes, you would not think the Sun is any louder than the ocean.
What is the loudest atmosphere in the solar system? The wind generates infrasound in the atmosphere and ocean. The faster the wind, the louder the noise and the lower the frequency of the noise. That means the 400 mph winds of Jupiter or the 1000 mph winds of Saturn would generate a lot of infrasound in their atmospheres. Rather than the Sun, it seems that Saturn would have the loudest atmosphere.
End note: The simplest formula to estimate the loudness of a sound wave is L = 10 log(I/I0) = 10 log(ρ c u2/10-9).
Wednesday, March 11, 2015
Tuesday, February 24, 2015
This eclipse season runs until March 17, 2015.
Tuesday, February 17, 2015
SDO's fifth anniversary was covered by a nice story on CNN.
Congratulations Monica and Sebastien, and congratulations to the SDO team!
Thursday, February 12, 2015
We also attended the opening of the Solarium exhibit that features SDO imagery and SOHO sounds opened yesterday at the Goddard Visitor Center. It is a cool way to watch hi-res images from SDO. The people who built SDO came by and we celebrated SDO's anniversary. (A rather interesting review appeared on this website.)
Another Space Weather spacecraft was launched yesterday. Welcome to the universe DSCOVR! Now we have two reasons to celebrate February 11.
Tuesday, February 10, 2015
Since the launch AIA has taken over 100 million images, with HMI not that far behind at 80 million. EVE has returned over 12 million EUV spectra of the Sun. There have been many science results, with over 2000 papers so far presenting SDO science results. My favorite observations include the trebuchet eruption, comets in the corona, and the Transit of Venus in 2012.
SDO is a great observatory! How about 5 more years?
Wednesday, February 4, 2015
Once the maneuvers are complete the usual data taking will resume.
Monday, February 2, 2015
SDO is a great example of how astronomers use light to measure and understand our universe. AIA and EVE look at light from the Sun at very short, extreme ultraviolet, wavelengths. By comparing AIA images we can detect small motions of the corona. HMI looks at visible light. One nice property of light is that we can measure how it interacts with the Sun to measure things at the Sun that are otherwise difficult (if not impossible) to measure. We use the Doppler shift to see the wave motions and the Zeeman effect to see the magnetic field at the surface.
Light is a wonderful thing!
Wednesday, January 28, 2015
Tomorrow is the AIA GT/PZT Calibration from 1500-1620 UTC (10:00-11:20 am ET), which should cause few problems with the SDO data.
Next Wednesday, February 4, 2015, SDO will perform two maneuvers, the EVE FOV from 1315-1557 UTC (5:15-10:57 am ET) and the HMI/AIA Flat Field from 1630-1907 UTC (11:30 am - 2:07 pm ET). During these maneuvers the images may be blurred.
Thursday, January 22, 2015
There is heavy snow at the White Sands Complex near Las Cruces, NM. About 6" of snow has fallen so far. Snow can cause the Ka-band science downlink to fade, and it completely faded at 1815 UTC (1:15 p.m. ET) and has not yet returned at 1915 UTC (2;15 p.m. ET). The S-band link is not affected by the snow and is still being received. When the snowfall abates we will again receive the science data.
Update 23-Jan-2015: Normal science data flow was restarted at 2204 UTC yesterday (5:04 p.m. ET). Many thanks to the people who cleaned the snow off the antennas!
Tuesday, January 20, 2015
The AIA team at LMSAL worked hard to design and build the AIA telescopes, even overcoming a delayed start way back at the beginning of the SDO project. The team continues to operate the instrument, keeping it calibrated and listing the features seen on the Sun. The HMI JSOC team at Stanford University maintains the archive that serves the images to our large and growing number of users.
Congratulations to the AIA team at LMSAL for designing, building, and running an excellent instrument for studying the Sun!
Thursday, January 15, 2015
The number 100,000,000 has been on my mind this week, especially as Monday approaches.
If I traveled 100,000,000 miles I could have gone to the Sun and been 7,000,000 miles on my way home by now.
100,000,000 seconds ago was Nov. 19, 2011, a day without great significance in my calendar.
100,000,000 people lived in the USA in 1914.
Here's a hint. SDO started returning science data on May 1, 2010. Tune in next week to find out what's up with 100,000,000!
Wednesday, January 14, 2015
Monday, January 5, 2015
Our orbit around the Sun is almost a circle right now. That means our seasons are caused by tilt of our rotation axis. But there have been times in the past when our orbit was more of an oval. It's fun to think about what that would do to our seasons and climate. The Lensman books by E. E. Doc Smith included a nemesis with a home planet that had an extremely elliptical orbit and the bizarre evolutionary adaptations that led to.
Thursday, January 1, 2015
There were no fireworks on the Sun last night to welcome in the New Year. Only a few C-class flares during the last day of 2014. Instead, the Sun starts 2015 with an enormous coronal hole near the South Pole. Here is an AIA 193 Å image from January 1, 2015 showing the coronal hole as a dark region in the south.
Coronal holes are regions of the corona where the magnetic field reaches out into space rather than looping back down onto the surface. Particles moving along those magnetic fields can leave the Sun rather than being trapped near the surface. Those trapped particles can heat up and glow, giving us the lovely AIA images. In the parts of the corona where the particles leave the Sun the glow is much dimmer and the coronal hole looks dark.
Coronal holes were first seen in images taken by astronauts on board NASA’s Skylab space station in 1973 and 1974. They can be seen for a long time, although the exact shape changes all the time. The polar coronal hole can remain visible for five years or longer. Each time a coronal hole rotates by the Earth we can measure the particles flowing out of the hole as a high-speed stream, another source of Space Weather.
Charged particles in the Earth’s radiation belts are accelerated when the high-speed stream runs into the Earth’s magnetosphere. The acceleration of particles in the magnetosphere is studied by NASA’s Van Allen Storm Probe mission.
As Solar Cycle 24 fades, the number of flares each day will get smaller, but the coronal holes provide another source of Space Weather that needs to be understood and predicted.
Happy New Year!