Below are definitions of some of the terms most commonly used for the Stardust@home project, as well as a few FAQs around the more common technical problems you might encounter. However, if there is anything you still don’t understand or need assistance with, please let us know.



Focus Movie

A stack of images taken from a single field of view of the automated microscope at several different focus depths. Each image can be thought of as a frame in a movie; running the movie forward and backward by sliding your mouse up and down the focus bar in the Virtual Microscope is equivalent to looking through a real microscope and turning the focus knob.

Power Movie

A Focus Movie which is known to contain a real track, although some of the tracks are man-made and some have been digitally inserted into the focus movie. All Power Movies have been assigned a difficulty value. Values can range between 5 and 85 points based on the measured success of all Stardust@home volunteers (aka Dusters) correctly identifying each track in Phase IV. The higher the value of the Power Movie, the more difficult it is to find the track it contains. Some Power Movies will be nearly impossible to spot. In order to collect data on the range of our volunteers’ abilities, most Power Movies above 70 points cannot be correctly identified. This is on purpose and thus you should not concern yourself too much with missing Power Movies of such value.

Power Score

Your Power Score is the total combined value of all Power Movies you have correctly identified (see Power Movie definition above). Note: If you miss a Power Movie, your Power Score will not go down.

Skill Score

Your Skill Score is a measure of how often you are able to identify a track when a Power Movie is presented to you (see Power Movie definition above). Your Skill Score will rise with every correctly identified Power Movie, depending on its value. It will also drop after every missed Power Movie in proportion to Power Movie difficulty. It will fall slightly for difficult (high value) Power Movies and fall more for less difficult (lower value) Power Movies. Your Skill Score equals your Power Score divided by your Power Score plus an adjustment for the difficulty (value) of the Power Movies you’ve missed from the last 100 Power Movies you’ve clicked on. Each time you miss a Power Movie, the adjustment is calculated as 85 minus the value of the missed Power Movie. A running total is then kept of this adjustment and used to calculate your Skill Score. The formula can also be expressed as follows: Skill Score = Power Score / {Power Score + running total of adjustments}, where each adjustment = (85 – missed Power Movie value). Note: In Phase VI, your Skill Score will be a more accurate representation of your current dusting skill. Instead of reflecting your abilities from when you started dusting in Phase VI, your Skill Score will always be based on the last 100 Power Movies you’ve searched over the last 60 days. If you haven’t clicked on 100 Power Movies over the last 60 days, your Skill Score will not display. Otherwise, the Skill Score formula remains the same as it was in Phase V.


A field of view, particularly in a microscope. Pronounced “fove”.

List of Data Viewed

Listing of track candidates that you have identified.

Number of Agreements

In the My Events page: the number of people who agreed with you that a certain movie really does contain a track. This number includes yourself!


Your rank is determined by comparing your score to the scores of other volunteers. If your rank is 150, that means there are 149 volunteers who have a higher score than you do. Your rank is recalculated every few minutes.

Real Movie

An ordinary focus movie, created from the aerogel that flew on the Stardust mission. (As opposed to a Calibration Movie.)


Virtual Microscope, the program used by Stardust@home allowing volunteers to view focus movies from the Stardust Interstellar Dust Collector.


On the MyEvents page, in the comments column, short-hand for “Worth Checking Out”.

For Phases I, II, and III only:


Your score is the total number of calibration movies you have identified correctly minus the number of calibration movies you have answered incorrectly. Most movies are not calibration movies, and will not affect your score. Score was replaced with Power Score in Phase IV.


Sensitivity measures how well you are able to correctly identify calibration tracks. Sensitivity is the total number of tracks you have correctly identified in calibration movies divided by the total number of calibration movies you have searched in which there were actually tracks.


Specificity measures how well you are able to correctly identify a calibration movie that contains no track. Specificity is the total number of times you have correctly found no track in calibration movies divided by the total number of calibration movies you have searched in which there were actually no tracks.


Tech FAQ

System Requirements

The virtual microscope (VM) is designed to work on a networked computer running any modern operating system and internet browser with JavaScript enabled.

Internet Connection

The VM does not require installation of any applications from Stardust@home.

Each focus movie (FOV) constitutes a 0.5 Mb download, or approximately 40 12 kbyte sized jpeg images. A dial-up internet connection (~40 kbps) will require about 90 seconds per movie. Dial-up users are not precluded from taking part in the stardust@home search, but we do recommend a faster connection for ease of use.

With a fast internet connection you should see no delay as you click through the movies as the next movie downloads in the background (but read on for some browser specific issues).

Operating systems

We have tested and received positive feedback from users of Mac OS X 10.2 and above, Windows XP, 7, and 8 versions (We have not tested under 8.1), and Linux and Unix. We have not tested or received feedback about Mac OS 9.x


Windows browsers: the latest versions of Internet Explorer, Chrome, Firefox.

Mac OS X browsers: the latest versions of Safari, Chrome, Firefox.

Virtual Microscope technical problems

The majority of problems encountered are browser specific, and often mitigated by switching to a different browser.